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 A343472 #7 Apr 16 2021 15:47:14 %S A343472 1,1,0,-2,0,4,12,-8,-48,-56,-144,400,1200,1792,960,16864,-34560, %T A343472 -170816,-320064,-632960,-869376,-15780224,30636288,144493312, %U A343472 360770304,738095104,2382729216,6661606912,81815537664,-152267942912,-883849860096,-2187970242560,-6499788165120 %N A343472 G.f.: 1 + 1!*x/(1 + 2!*x^2/(1 + 3!*x^3/(1 + 4!*x^4/(1 + 5!*x^5/(1 + ...))))). %o A343472 (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 A343472 Cf. A285381, A343428. %K A343472 sign %O A343472 0,4 %A A343472 _Seiichi Manyama_, Apr 16 2021