This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A151684 #6 Jan 04 2021 03:49:01
%S A151684 1,1,1,0,-1,1,1,-1,0,0,-2,1,2,0,2,-1,-5,-1,1,3,7,1,-8,-8,-6,3,18,16,0,
%T A151684 -17,-31,-21,19,51,47,3,-70,-106,-48,71,170,156,-18,-243,-318,-132,
%U A151684 253,564,455,-130,-819,-1024,-341,952,1849,1355,-606,-2789,-3199,-727,3410,5979,3932,-2678,-9408,-9926,-1281,12047
%N A151684 Let c(n) = x^(2^n-1)*(1-x^(2^n)), g(n) = 1 + x^(2^n-1) + x^(2^n), h(n) = Product_{i=1..n} g(i); then use g.f. (1+2*x) - Sum_{n>=1} c(n)/h(n).
%C A151684 This g.f. multiplied by h(k) for k large (cf. A151552) gives the g.f. for (A160573 prefixed by an initial 1).
%Y A151684 Cf. A151676, A160573, A151552.
%K A151684 sign
%O A151684 0,11
%A A151684 _N. J. A. Sloane_, Jun 01 2009