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 A343468 #8 Apr 16 2021 15:47:09 %S A343468 1,1,0,-2,0,4,6,-8,-24,-2,48,76,-42,-224,-144,406,744,-332,-2154, %T A343468 -1400,4320,7702,-2016,-21428,-17802,34216,76152,-5210,-195816, %U A343468 -181916,300510,772432,53136,-1851770,-2055360,2388772,7515246,1755880,-16586616,-21354266,19195248,72641884,27527118 %N A343468 G.f.: 1 + 1*x/(1 + 2*x^2/(1 + 3*x^3/(1 + 4*x^4/(1 + 5*x^5/(1 + ...))))). %o A343468 (PARI) a(n) = my(A=1+O(x)); for(i=1, n, A=1+(n-i+1)*x^(n-i+1)/A); polcoef(A, n); %Y A343468 Cf. A000698, A003823, A088357, A343472, A343473. %K A343468 sign %O A343468 0,4 %A A343468 _Seiichi Manyama_, Apr 16 2021