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 A384576 #13 Jun 04 2025 09:52:47 %S A384576 1,2,3,8,27,118,609,3602,23866,174186,1383868,11860702,108889022, %T A384576 1064691402,11034753421,120739899232,1389891203976,16781698952902, %U A384576 211959646629376,2793804347189762,38347179124969391,547046497259184494,8096627908313404104 %N A384576 G.f. A(x) satisfies A(x) = ( 1 + x * A(x*A(x))^(1/2) )^2. %F A384576 See A384580. %F A384576 G.f.: B(x)^2, where B(x) is the g.f. of A143500. %o A384576 (PARI) a(n, k=2) = if(k==0, 0^n, k*sum(j=0, n, binomial(2*n-2*j+k, j)/(2*n-2*j+k)*a(n-j, j))); %Y A384576 Column k=2 of A384580. %Y A384576 Cf. A143500. %K A384576 nonn %O A384576 0,2 %A A384576 _Seiichi Manyama_, Jun 04 2025