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 A217284 #19 Jan 05 2024 06:43:35
%S A217284 1,2,17,460,29441,3680126,794907217,272653175432,139598425821185,
%T A217284 101767252423643866,101767252423643866001,135452212975869985647332,
%U A217284 234061424022303335198589697,514232948577000427431301564310,1411055210895289172871491492466641,4762311336771600958441283787074913376
%N A217284 a(n) = Sum_{k=0..n} (n!/k!)^3.
%H A217284 Vincenzo Librandi, <a href="/A217284/b217284.txt">Table of n, a(n) for n = 0..180</a>
%F A217284 Recurrence: a(n) = (n+1)*(n^2-n+1)*a(n-1)-(n-1)^3*a(n-2).
%F A217284 a(n) ~ 2.12970254898330641813452361... * (n!)^3 = A271574 * (n!)^3.
%F A217284 a(n) = n^3 * a(n-1) + 1. - _Seiichi Manyama_, May 02 2021
%t A217284 Table[Sum[(n!/k!)^3, {k, 0, n}], {n, 0, 20}]
%o A217284 (PARI) a(n) = sum(k=0, n, (n!/k!)^3); \\ _Seiichi Manyama_, May 02 2021
%Y A217284 Cf. A000522, A006040, A271574, A336247.
%K A217284 nonn
%O A217284 0,2
%A A217284 _Vaclav Kotesovec_, Sep 30 2012