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 A336828 #15 Feb 20 2021 11:03:32 %S A336828 1,1,8,108,2144,56250,1836792,71799504,3269445888,169974711630, %T A336828 9934458411800,644825382429096,46022332032100800,3582265183110626740, %U A336828 302002255041807372080,27413749834141448520000,2665789990569658618398720,276477318687585566522176470 %N A336828 a(n) = Sum_{k=0..n} binomial(n,k)^2 * k^n. %H A336828 Seiichi Manyama, <a href="/A336828/b336828.txt">Table of n, a(n) for n = 0..343</a> %F A336828 a(n) ~ c * d^n * (n-1)!, where d = (1 + 2*LambertW(exp(-1/2)/2)) / (4*LambertW(exp(-1/2)/2)^2) = 6.476217542109791521947605963458797355564... and c = 0.21617818094152997942246965143216887599763501682724844713834495... - _Vaclav Kotesovec_, Feb 20 2021 %t A336828 Join[{1}, Table[Sum[Binomial[n, k]^2 k^n, {k, 0, n}], {n, 1, 17}]] %o A336828 (PARI) a(n) = sum(k=0, n, binomial(n, k)^2*k^n); \\ _Michel Marcus_, Aug 05 2020 %Y A336828 Cf. A000984, A002457, A037966, A037972, A072034, A074334, A187021, A329444, A329913, A336214, A341815. %K A336828 nonn %O A336828 0,3 %A A336828 _Ilya Gutkovskiy_, Aug 05 2020