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 A367331 #6 Nov 14 2023 17:26:57 %S A367331 1,24,657,17664,477828,12888288,348197220,9397548288,253804616001, %T A367331 6851337236952,185014241769825,4994797849546752,134872057740184128, %U A367331 3641273395825798656,98320397048549301312,2654515896013953110016,71674988018612154171876 %N A367331 a(n) = 27^n * Sum_{k=0..n} (-1)^k*binomial(1/3, k)^2. %C A367331 In general, for m>1, Sum_{k>=0} (-1)^k * binomial(1/m,k)^2 = 2^(1/m) * sqrt(Pi) / (Gamma(1 + 1/(2*m)) * Gamma(1/2 - 1/(2*m))). %F A367331 a(n) ~ 2^(5/3) * Pi * 3^(3*n + 1/2) / Gamma(1/3)^3. %t A367331 Table[27^n*Sum[(-1)^k*Binomial[1/3, k]^2, {k, 0, n}], {n, 0, 16}] %Y A367331 Cf. A358363, A367330, A367332, A367333. %K A367331 nonn %O A367331 0,2 %A A367331 _Vaclav Kotesovec_, Nov 14 2023