A309026 - OEIS

%I #7 Jul 07 2019 20:20:01

%S 0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,3,

%T 2,2,1,3,2,2,1,3,2,2,1,3,2,2,1,4,2,2,1,4,2,2,1,4,2,2,1,4,2,2,1,5,3,3,

%U 2,4,2,2,1,5,3,3,2,4,2,2,1,6,3,4,2,4,2,2,1,6,3,4,2,4,2,2,1,7,4,4,2

%N Expansion of x * Product_{k>=0} (1 + x^(2^k) + x^(2^(k+4))).

%F a(n) = 0 for n <= 0, a(1) = 1; a(2*n) = a(n), a(2*n+1) = a(n-7) + a(n+1).

%t nmax = 100; CoefficientList[Series[x Product[(1 + x^(2^k) + x^(2^(k + 4))), {k, 0, Floor[Log[2, nmax]] + 1}], {x, 0, nmax}], x]

%Y Cf. A002487, A112970, A309025.

%K nonn

%O 0,18

%A _Ilya Gutkovskiy_, Jul 07 2019