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 A171201 #7 Apr 02 2025 16:10:04 %S A171201 1,3,21,289,7566,380424,37361616,7252471584,2799853666176, %T A171201 2155959119115264,3315891500224031232,10193070293871040606464, %U A171201 62646640175842537242599936,769927299959295414569740867584,18923273743619678311418282019397632,930154604531789703005691292148132511744 %N A171201 G.f. satisfies: A(x) = (1 + x*A(2x))^3. %F A171201 Self-convolution cube of A171200 where a(n) = A171200(n+1)/2^n for n>=0. %t A171201 terms = 16; A[_] = 0; Do[A[x_] = (1 + x*A[2x])^3 + O[x]^terms // Normal, terms]; CoefficientList[A[x], x] (* _Stefano Spezia_, Apr 02 2025 *) %o A171201 (PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=(1+x*subst(A, x, 2*x))^3); polcoeff(A, n)} %Y A171201 Cf. A135868, A171200, A171202-A171211. %K A171201 nonn %O A171201 0,2 %A A171201 _Paul D. Hanna_, Dec 05 2009 %E A171201 a(14)-a(15) from _Stefano Spezia_, Apr 02 2025