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 A166999 #4 Sep 22 2024 14:04:01 %S A166999 1,3,39,60879,225636660844959, %T A166999 11487591726386681145142587842614325062822719 %N A166999 a(n) = a(n-1) + a(n-1)^2 + a(n-1)^3 for n>0 with a(0)=1. %F A166999 Row sums of triangle A166880, which lists the coefficients in the iterations of x+x^2+x^3. %t A166999 NestList[#+#^2+#^3&,1,5] (* _Harvey P. Dale_, Sep 22 2024 *) %o A166999 (PARI) a(n)=if(n==0,1,a(n-1)+a(n-1)^2+a(n-1)^3) %Y A166999 Cf. A166880. %K A166999 nonn %O A166999 0,2 %A A166999 _Paul D. Hanna_, Nov 21 2009