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 A343439 #26 Apr 16 2021 09:04:11
%S A343439 1,1,-2,12,-136,2736,-99616,6810816,-900563072,234247256832,
%T A343439 -120883821425152,124271556482829312,-255006726559759042560,
%U A343439 1045529090595650037657600,-8569159507007490469146992640,140431398588497630920722150113280,-4602217897540461023955069241211781120
%N A343439 G.f.: 1 + 2^0*x/(1 + 2^1*x/(1 + 2^2*x/(1 + 2^3*x/(1 + 2^4*x/(1 + ...))))).
%H A343439 Seiichi Manyama, <a href="/A343439/b343439.txt">Table of n, a(n) for n = 0..81</a>
%F A343439 G.f. satisfies: A(x) = 1 + x/A(2*x).
%F A343439 G.f.: 1/(Sum_{k>=0} A015083(k) * (-x)^k).
%F A343439 a(0) = a(1) = 1 and a(n) = -Sum_{k=1..n-1} 2^k*a(k)*a(n-k) for n > 1.
%F A343439 a(n) = (-2)^(n-1) * A015083(n-1) for n > 0.
%o A343439 (PARI) a(n) = my(A=1+O(x)); for(i=1, n, A=1+2^(n-i)*x/A); polcoef(A, n);
%o A343439 (PARI) a(n) = if(n<2, 1, -sum(k=1, n-1, 2^k*a(k)*a(n-k)));
%Y A343439 Cf. A015083, A168491, A216966.
%K A343439 sign
%O A343439 0,3
%A A343439 _Seiichi Manyama_, Apr 15 2021