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 A381649 #10 Mar 03 2025 06:47:08 %S A381649 1,1,5,44,510,7024,109362,1871530,34590180,682396379,14251399805, %T A381649 313170119013,7207845252630,173129413258492,4327373963163746, %U A381649 112289379643018983,3018922654575996866,83951253980821314446,2411137697712963195801,71427857356498491780290 %N A381649 G.f. A(x) satisfies A(x) = 1 + x * A(x)^2 * A(x*A(x)^3)^3. %F A381649 See A381648. %o A381649 (PARI) a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(3*n-j+k, j)/(3*n-j+k)*a(n-j, 3*j))); %Y A381649 Column k=1 of A381648. %Y A381649 Cf. A120973, A212029, A381601, A381615. %Y A381649 Cf. A087949, A381029. %K A381649 nonn %O A381649 0,3 %A A381649 _Seiichi Manyama_, Mar 03 2025