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 A383138 #10 Apr 17 2025 12:27:50
%S A383138 0,1,20,189,1320,7785,41148,201285,929232,4100625,17452260,72098829,
%T A383138 290521080,1146082041,4439303820,16923738645,63619864992,236206924065,
%U A383138 867305334708,3152957079645,11359168737480,40589657212041,143957705302620,507079568653029
%N A383138 a(n) = Sum_{k=0..n} k^4 * 2^(n-k) * binomial(n,k).
%F A383138 a(n) = 3^(n-4) * n * (-6 + 20*n + 12*n^2 + n^3).
%o A383138 (PARI) a(n) = 3^(n-4)*n*(-6+20*n+12*n^2+n^3);
%Y A383138 Cf. A027471, A383136, A383137, A383139.
%K A383138 nonn,easy
%O A383138 0,3
%A A383138 _Seiichi Manyama_, Apr 17 2025