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 A381570 #14 Mar 01 2025 08:34:54 %S A381570 1,3,12,82,732,7944,99156,1381464,21065853,346932822,6112226961, %T A381570 114383442888,2261347164766,47025363829497,1025005545866361, %U A381570 23349137897005296,554467427766694440,13696046757037152183,351231525904387758222,9335221780768641038952 %N A381570 G.f. A(x) satisfies A(x) = (1 + x*A(x*A(x)))^3. %F A381570 See A381569. %F A381570 G.f.: B(x)^3, where B(x) is the g.f. of A212029. %o A381570 (PARI) a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(3*n-3*j+3*k, j)/(n-j+k)*a(n-j, j))); %Y A381570 Column k=1 of A381569. %Y A381570 Cf. A087949, A120972, A212029, A381568, A381574. %K A381570 nonn %O A381570 0,2 %A A381570 _Seiichi Manyama_, Feb 28 2025