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 A183035 #7 Mar 12 2022 13:22:13
%S A183035 1,0,-1,0,3,0,-3,0,3,0,-3,0,1,0,-1,0,3,0,-3,0,9,0,-9,0,9,0,-9,0,3,0,
%T A183035 -3,0,3,0,-3,0,9,0,-9,0,9,0,-9,0,3,0,-3,0,1,0,-1,0,3,0,-3,0,3,0,-3,0,
%U A183035 1,0,-1,0,3,0,-3,0,9,0,-9,0,9,0,-9,0,3,0,-3,0,9,0,-9,0,27,0,-27,0,27,0,-27,0,9,0
%N A183035 G.f.: A(x) = x*(1-x^2)*Product_{n>=1} (1 + x^(4^n))^3.
%F A183035 a(2n) = 0.
%e A183035 G.f.: A(x) = x - x^3 + 3*x^5 - 3*x^7 + 3*x^9 - 3*x^11 + x^13 - x^15 +...
%o A183035 (PARI) {a(n)=local(L4n=ceil(log(n+1)/log(4)));polcoeff(x*(1-x^2)*prod(k=1,L4n,1 + x^(4^k)+x*O(x^n))^3,n)}
%Y A183035 Cf. A183034.
%K A183035 sign
%O A183035 1,5
%A A183035 _Paul D. Hanna_, Dec 19 2010