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 A353041 #7 May 06 2022 15:12:21
%S A353041 1,1,4,34,820,62140,14651728,10547347384,22950318347248,
%T A353041 150277943334242320,2955664382713520203072,
%U A353041 174478760893191691170298912,30905073486465684713191125079360,16423574117627547687292156418920831936,26184104208316120602662312616366633316565248
%N A353041 G.f. A(x) satisfies: A(x) = 1 + x * A(3*x/(1 + 2*x)) / (1 - x).
%F A353041 G.f.: Sum_{k>=0} 3^(k*(k-1)/2) * (x/(1 - x))^k.
%F A353041 a(n) = Sum_{k=0..n} binomial(n-1,k-1) * 3^(k*(k-1)/2).
%t A353041 nmax = 14; A[_] = 0; Do[A[x_] = 1 + x A[3 x/(1 + 2 x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
%t A353041 Table[Sum[Binomial[n - 1, k - 1] 3^(k (k - 1)/2), {k, 0, n}], {n, 0, 14}]
%Y A353041 Cf. A006898, A047656, A135755 (partial sums), A353042.
%K A353041 nonn
%O A353041 0,3
%A A353041 _Ilya Gutkovskiy_, Apr 19 2022