A209668 - OEIS

%I #33 May 10 2021 07:41:16

%S 1,1,7,55,631,8001,130453,2323483,48916087,1129559068,29442232007,

%T 835245785452,26113646252773,880685234758941,32191922753658129,

%U 1259701078978200555,52802268925363689079,2352843030410455053891,111343906794849929711260,5567596199767400904172045

%N a(n) = count of monomials, of degree k = n, in the complete homogeneous symmetric polynomials h(mu,k) summed over all partitions mu of n.

%C a(n) is the number of partitions of n where each part i is marked with a word of length i over an n-ary alphabet whose letters appear in alphabetical order. a(2) = 7: 2aa, 2ab, 2bb, 1a1a, 1a1b, 1b1a, 1b1b. - _Alois P. Heinz_, Aug 30 2015

%H Alois P. Heinz, <a href="/A209668/b209668.txt">Table of n, a(n) for n = 0..386</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Symmetric_polynomials">Symmetric Polynomials</a>

%F a(n) ~ c * n^n, where c = A247551 = Product_{k>=2} 1/(1-1/k!) = 2.529477472... . - _Vaclav Kotesovec_, Nov 15 2016

%F a(n) = [x^n] Product_{k>=1} 1 / (1 - binomial(k+n-1,n-1)*x^k). - _Ilya Gutkovskiy_, May 09 2021

%p b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,

%p       add(b(n-i*j, i-1, k)*binomial(i+k-1, k-1)^j, j=0..n/i)))

%p     end:

%p a:= n-> b(n$3):

%p seq(a(n), n=0..25);  # _Alois P. Heinz_, Aug 29 2015

%t h[n_, v_] := Tr@ Apply[Times, Table[Subscript[x, j], {j, v}]^# & /@ Compositions[n, v], {1}]; h[par_?PartitionQ, v_] := Times @@ (h[#, v] & /@ par); Tr /@ Table[(h[#, l] & /@ Partitions[l]) /. Subscript[x, _] -> 1, {l, 10}]

%t b[n_, i_, k_] := b[n, i, k] = If[n==0, 1, If[i<1, 0, Sum[b[n-i*j, i-1, k] * Binomial[i+k-1, k-1]^j, {j, 0, n/i}]]]; a[n_] := b[n, n, n]; Table[a[n], {n, 0, 25}] (* _Jean-François Alcover_, Jan 15 2016, after _Alois P. Heinz_ *)

%Y Cf. A209664-A209673.

%Y Main diagonal of A209666 and A261718.

%Y Cf. A261783.

%K nonn

%O 0,3

%A _Wouter Meeussen_, Mar 11 2012

%E a(0)=1 prepended and a(11)-a(19) added by _Alois P. Heinz_, Aug 29 2015