A binary hook-length formula? Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern) Announcing the arrival of Valued Associate #679: Cesar Manara Unicorn Meta Zoo #1: Why another podcast?Finite nilpotent orbits: GL(n,q)-conjugacy classes and a partial order on partitionsLinking formulas by Euler, Pólya, Nekrasov-Okounkovpartitions into odd parts vs hooks and symplectic contentshooks and contents: Part IHooks in a staircase partition: Part IA link between hooks, contents and parts of a partitionA link between hooks and contents: Part IIGenerating function for $3$-core partitionsGenerating function for 3 -core partitions: Part IIhook-length formula: “Fibonaccized” Part I

A binary hook-length formula?



Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)
Announcing the arrival of Valued Associate #679: Cesar Manara
Unicorn Meta Zoo #1: Why another podcast?Finite nilpotent orbits: GL(n,q)-conjugacy classes and a partial order on partitionsLinking formulas by Euler, Pólya, Nekrasov-Okounkovpartitions into odd parts vs hooks and symplectic contentshooks and contents: Part IHooks in a staircase partition: Part IA link between hooks, contents and parts of a partitionA link between hooks and contents: Part IIGenerating function for $3$-core partitionsGenerating function for 3 -core partitions: Part IIhook-length formula: “Fibonaccized” Part I










5












$begingroup$


This is purely exploratory and inspired by curiosity.



Setup: For an integer $k>0$, let $k=sum_jgeq0k_j2^j$ be its binary expansion and denote the sum of its digits by $eta(k):=sum_jk_j$. Further, introduce a binary factorial
$$[n]!_b:=eta(1)eta(2)cdotseta(n).$$
Given an integer partition $lambda$, let $Y_lambda$ be the corresponding Young diagram. If $square$ a cell in $Y_lambda$, construct its hook-length $h_square$ in the usual manner but replace it by $eta(h_square)$.



For example, take $lambda=(3,2,1)$ then its multiset of hooks is $h_square:squarein Y_lambda=5,3,1,3,1,1$ which shall be replaced by $eta(h_square):squarein Y_lambda=2,2,1,2,1,1$.



Naturally, we define the (new) product of hook-lengths and denote (with an abuse of notation)
$$H_lambda=prod_squareinlambdaeta(h_square).$$
If $lambdavdash n$, it is easy to verify that $frac[n]!_bH_lambda$ is an integer.




QUESTION. What do these integer count?
$$sum_lambdavdash nfrac[n]!_bH_lambda.$$




The first few values are: $1, 2, 3, 7, 10, 23, 52, 82, 117, 258, dots$ but not listed on OEIS.










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$endgroup$
















    5












    $begingroup$


    This is purely exploratory and inspired by curiosity.



    Setup: For an integer $k>0$, let $k=sum_jgeq0k_j2^j$ be its binary expansion and denote the sum of its digits by $eta(k):=sum_jk_j$. Further, introduce a binary factorial
    $$[n]!_b:=eta(1)eta(2)cdotseta(n).$$
    Given an integer partition $lambda$, let $Y_lambda$ be the corresponding Young diagram. If $square$ a cell in $Y_lambda$, construct its hook-length $h_square$ in the usual manner but replace it by $eta(h_square)$.



    For example, take $lambda=(3,2,1)$ then its multiset of hooks is $h_square:squarein Y_lambda=5,3,1,3,1,1$ which shall be replaced by $eta(h_square):squarein Y_lambda=2,2,1,2,1,1$.



    Naturally, we define the (new) product of hook-lengths and denote (with an abuse of notation)
    $$H_lambda=prod_squareinlambdaeta(h_square).$$
    If $lambdavdash n$, it is easy to verify that $frac[n]!_bH_lambda$ is an integer.




    QUESTION. What do these integer count?
    $$sum_lambdavdash nfrac[n]!_bH_lambda.$$




    The first few values are: $1, 2, 3, 7, 10, 23, 52, 82, 117, 258, dots$ but not listed on OEIS.










    share|cite|improve this question











    $endgroup$














      5












      5








      5


      2



      $begingroup$


      This is purely exploratory and inspired by curiosity.



      Setup: For an integer $k>0$, let $k=sum_jgeq0k_j2^j$ be its binary expansion and denote the sum of its digits by $eta(k):=sum_jk_j$. Further, introduce a binary factorial
      $$[n]!_b:=eta(1)eta(2)cdotseta(n).$$
      Given an integer partition $lambda$, let $Y_lambda$ be the corresponding Young diagram. If $square$ a cell in $Y_lambda$, construct its hook-length $h_square$ in the usual manner but replace it by $eta(h_square)$.



      For example, take $lambda=(3,2,1)$ then its multiset of hooks is $h_square:squarein Y_lambda=5,3,1,3,1,1$ which shall be replaced by $eta(h_square):squarein Y_lambda=2,2,1,2,1,1$.



      Naturally, we define the (new) product of hook-lengths and denote (with an abuse of notation)
      $$H_lambda=prod_squareinlambdaeta(h_square).$$
      If $lambdavdash n$, it is easy to verify that $frac[n]!_bH_lambda$ is an integer.




      QUESTION. What do these integer count?
      $$sum_lambdavdash nfrac[n]!_bH_lambda.$$




      The first few values are: $1, 2, 3, 7, 10, 23, 52, 82, 117, 258, dots$ but not listed on OEIS.










      share|cite|improve this question











      $endgroup$




      This is purely exploratory and inspired by curiosity.



      Setup: For an integer $k>0$, let $k=sum_jgeq0k_j2^j$ be its binary expansion and denote the sum of its digits by $eta(k):=sum_jk_j$. Further, introduce a binary factorial
      $$[n]!_b:=eta(1)eta(2)cdotseta(n).$$
      Given an integer partition $lambda$, let $Y_lambda$ be the corresponding Young diagram. If $square$ a cell in $Y_lambda$, construct its hook-length $h_square$ in the usual manner but replace it by $eta(h_square)$.



      For example, take $lambda=(3,2,1)$ then its multiset of hooks is $h_square:squarein Y_lambda=5,3,1,3,1,1$ which shall be replaced by $eta(h_square):squarein Y_lambda=2,2,1,2,1,1$.



      Naturally, we define the (new) product of hook-lengths and denote (with an abuse of notation)
      $$H_lambda=prod_squareinlambdaeta(h_square).$$
      If $lambdavdash n$, it is easy to verify that $frac[n]!_bH_lambda$ is an integer.




      QUESTION. What do these integer count?
      $$sum_lambdavdash nfrac[n]!_bH_lambda.$$




      The first few values are: $1, 2, 3, 7, 10, 23, 52, 82, 117, 258, dots$ but not listed on OEIS.







      nt.number-theory co.combinatorics rt.representation-theory partitions






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      edited 2 days ago







      T. Amdeberhan

















      asked 2 days ago









      T. AmdeberhanT. Amdeberhan

      18.5k230132




      18.5k230132




















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          $begingroup$

          I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.






          share|cite|improve this answer









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            10












            $begingroup$

            I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.






            share|cite|improve this answer









            $endgroup$

















              10












              $begingroup$

              I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.






              share|cite|improve this answer









              $endgroup$















                10












                10








                10





                $begingroup$

                I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.






                share|cite|improve this answer









                $endgroup$



                I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered 2 days ago









                Fedor PetrovFedor Petrov

                52.4k6122241




                52.4k6122241



























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