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A272518 Number of set partitions of [n] into six blocks with distinct sizes. 2

%I

%S 2053230379200,6453009763200,43288940494800,242418066770880,

%T 1707999012720000,12887361202716000,144924867388501200,

%U 620550897351184800,4048435123506774000,23424084614648718000,161250104584826056800,1013722794731975328000,8616255173755280251200

%N Number of set partitions of [n] into six blocks with distinct sizes.

%H Alois P. Heinz, <a href="/A272518/b272518.txt">Table of n, a(n) for n = 21..1000</a>

%F a(n) = n! * [x^n*y^6] Product_{n>=1} (1+y*x^n/n!).

%p b:= proc(n, i, t) option remember; `if`(t>i or t*(t+1)/2>n

%p or t*(2*i+1-t)/2<n, 0, `if`(n=0, 1, b(n,i-1,t)+

%p `if`(i>n, 0, b(n-i, i-1, t-1)*binomial(n,i))))

%p end:

%p a:= n-> b(n$2, 6):

%p seq(a(n), n=21..40);

%Y Column k=6 of A131632.

%K nonn

%O 21,1

%A _Alois P. Heinz_, May 01 2016

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Last modified April 8 22:35 EDT 2020. Contains 333331 sequences. (Running on oeis4.)