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 A384897 #9 Jun 12 2025 10:23:28 %S A384897 1,1,3,3,-8,-81,-462,-1140,1662,42210,341922,1588428,3968106, %T A384897 -17035461,-330216303,-2645037192,-15366663001,-56099904270, %U A384897 42126523152,2923843607931,33032055390075,253102960693959,1474460670302136,5496172108115193,-8530990617203547 %N A384897 G.f. A(x) satisfies A(x) = 1 + x/A(-x*A(x)^2)^3. %F A384897 See A384902. %o A384897 (PARI) a(n, k=-1) = if(n*k==0, 0^n, (-1)^n*k*sum(j=1, n, binomial(-2*n+3*j+k-1, j-1)*a(n-j, 3*j)/j)); %Y A384897 Column k=1 of A384902. %Y A384897 Cf. A001764, A213096, A384896, A384898. %K A384897 sign %O A384897 0,3 %A A384897 _Seiichi Manyama_, Jun 12 2025