A035398 - OEIS

%I #8 Aug 27 2015 06:14:58

%S 1,1,1,2,2,2,2,4,4,4,5,7,7,7,9,12,12,13,16,19,19,22,26,30,31,36,41,45,

%T 48,56,62,68,75,85,92,101,112,125,134,149,165,180,193,216,237,256,277,

%U 309,335,360,392,434,466,503,550,602,643,697,760,824,881,958,1039

%N Number of partitions of n into parts 7k+1 or 7k+4.

%F a(n) ~ exp(2*Pi*sqrt(n/21)) * Gamma(1/7) * Gamma(4/7) / (4 * 3^(3/28) * 7^(11/28) * Pi^(9/7) * n^(17/28)). - _Vaclav Kotesovec_, Aug 27 2015

%t nmax = 100; Rest[CoefficientList[Series[Product[1/((1 - x^(7k+1))*(1 - x^(7k+4))), {k, 0, nmax}], {x, 0, nmax}], x]] (* _Vaclav Kotesovec_, Aug 27 2015 *)

%K nonn

%O 1,4

%A _Olivier Gérard_