OFFSET
1,3
COMMENTS
A tableau is normal if its entries span an initial interval of positive integers. The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).
REFERENCES
Richard P. Stanley, Enumerative Combinatorics Volume 2, Cambridge University Press, 1999, Chapter 7.10.
LINKS
FindStat - Combinatorial Statistic Finder, Semistandard Young tableaux
FORMULA
Let b(n) = Sum_{d|n, d>1} b(n * d' / d) where if d = Product_i prime(s_i)^m(i) then d' = Product_i prime(s_i - 1)^m(i) and prime(0) = 1. Then a(n) = b(conj(n)) where conj = A122111.
EXAMPLE
The a(9) = 6 tableaux:
1 3 1 2 1 2 1 2 1 1 1 1
2 4 3 4 3 3 2 3 2 3 2 2
MATHEMATICA
conj[y_List]:=If[Length[y]===0, y, Table[Length[Select[y, #>=k&]], {k, 1, Max[y]}]];
conj[n_Integer]:=Times@@Prime/@conj[If[n===1, {}, Join@@Cases[FactorInteger[n]//Reverse, {p_, k_}:>Table[PrimePi[p], {k}]]]];
ssyt[n_]:=If[n===1, 1, Sum[ssyt[n/q*Times@@Cases[FactorInteger[q], {p_, k_}:>If[p===2, 1, NextPrime[p, -1]^k]]], {q, Rest[Divisors[n]]}]];
Table[ssyt[conj[n]], {n, 50}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Feb 14 2018
STATUS
approved