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 A381574 #12 Mar 02 2025 08:01:16 %S A381574 1,3,15,118,1206,14712,204385,3143826,52580328,944416084,18056415144, %T A381574 365065244238,7765839784508,173123253590079,4031536347783786, %U A381574 97807655876704029,2466489368705170539,64527021089110890192,1748298996924574135699,48982266056400514509660 %N A381574 G.f. A(x) satisfies A(x) = 1/(1 - x*A(x*A(x)))^3. %F A381574 See A381573. %F A381574 G.f.: B(x)^3, where B(x) is the g.f. of A381615. %o A381574 (PARI) a(n, k=1) = if(k==0, 0^n, 3*k*sum(j=0, n, binomial(3*n-2*j+3*k, j)/(3*n-2*j+3*k)*a(n-j, j))); %Y A381574 Column k=1 of A381573. %Y A381574 Cf. A381570, A381615. %K A381574 nonn %O A381574 0,2 %A A381574 _Seiichi Manyama_, Feb 28 2025