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 A367747 #13 Nov 29 2023 11:40:16
%S A367747 1,1,3,13,73,561,4771,49813,562353,7340833,102829411,1627648221,
%T A367747 27294311353,502042022353,9759264753603,205434011254501,
%U A367747 4544894700204001,107346788357502273,2657668122191037763,69701762677026498733,1909106308252976007081
%N A367747 E.g.f. satisfies A(x) = exp(x * (1 + x) * A(x^2)).
%F A367747 a(0) = 1; a(n) = (n-1)! * Sum_{k=0..n-1} (k+1) * a(floor(k/2)) * a(n-1-k) / (floor(k/2)! * (n-1-k)!).
%o A367747 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=(i-1)!*sum(j=0, i-1, (j+1)*v[j\2+1]*v[i-j]/((j\2)!*(i-1-j)!))); v;
%Y A367747 Cf. A000272, A367748, A367749, A367751.
%Y A367747 Cf. A127680, A138292.
%K A367747 nonn
%O A367747 0,3
%A A367747 _Seiichi Manyama_, Nov 29 2023