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 A036720 #5 Jul 08 2025 21:54:45 %S A036720 1,1,1,4,8,27,79,270,894,3130,11011,39622,143879,528919,1960248, %T A036720 7323999,27542451,104194485,396204388,1513599583,5806283770, %U A036720 22356914550,86376741339,334752355281,1300999638753,5069411676111,19800500391264 %N A036720 G.f. satisfies A(x) = 1 + x*cycle_index(Klein_4_group, A(x)). %Y A036720 Cf. A036717-A036719. %K A036720 nonn %O A036720 0,4 %A A036720 _N. J. A. Sloane_