cp's OEIS Frontend

A341388 Expansion of (-1 + Product_{k>=1} (1 + x^k)^k)^6.

%I A341388 #9 Feb 10 2021 18:50:41
%S A341388 1,12,90,508,2391,9840,36578,125358,402093,1220232,3532836,9821280,
%T A341388 26352110,68528718,173311971,427486178,1030855416,2435255634,
%U A341388 5645810201,12864839166,28850671284,63751119334,138946592610,298974483954,635626314025
%N A341388 Expansion of (-1 + Product_{k>=1} (1 + x^k)^k)^6.
%H A341388 Alois P. Heinz, <a href="/A341388/b341388.txt">Table of n, a(n) for n = 6..10000</a>
%p A341388 g:= proc(n) option remember; `if`(n=0, 1, add(g(n-j)*add(d^2/
%p A341388      `if`(d::odd, 1, 2), d=numtheory[divisors](j)), j=1..n)/n)
%p A341388     end:
%p A341388 b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0,
%p A341388       g(n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
%p A341388     end:
%p A341388 a:= n-> b(n, 6):
%p A341388 seq(a(n), n=6..30);  # _Alois P. Heinz_, Feb 10 2021
%t A341388 nmax = 30; CoefficientList[Series[(-1 + Product[(1 + x^k)^k, {k, 1, nmax}])^6, {x, 0, nmax}], x] // Drop[#, 6] &
%Y A341388 Cf. A026007, A321951, A327384, A341384, A341385, A341386, A341387, A341390, A341391.
%K A341388 nonn
%O A341388 6,2
%A A341388 _Ilya Gutkovskiy_, Feb 10 2021