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A258477 Number of partitions of n into two sorts of parts having exactly 7 parts of the second sort.

%I A258477 #4 May 31 2015 10:54:41
%S A258477 1,9,46,175,551,1517,3775,8677,18702,38221,74670,140380,255200,450587,
%T A258477 775050,1302820,2144491,3464614,5501502,8601609,13254960,20160072,
%U A258477 30285308,44987881,66117110,96226698,138744972,198343467,281212898,395689440,552693604,766773242
%N A258477 Number of partitions of n into two sorts of parts having exactly 7 parts of the second sort.
%H A258477 Alois P. Heinz, <a href="/A258477/b258477.txt">Table of n, a(n) for n = 7..1000</a>
%p A258477 b:= proc(n, i) option remember; series(`if`(n=0, 1,
%p A258477       `if`(i<1, 0, add(b(n-i*j, i-1)*add(x^t*
%p A258477        binomial(j, t), t=0..min(7, j)), j=0..n/i))), x, 8)
%p A258477     end:
%p A258477 a:= n-> coeff(b(n$2), x, 7):
%p A258477 seq(a(n), n=7..40);
%Y A258477 Column k=7 of A256193.
%K A258477 nonn
%O A258477 7,2
%A A258477 _Alois P. Heinz_, May 31 2015