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 A262960 #11 Oct 05 2015 17:34:14 %S A262960 1,21,661,28941,1678501,124467021,11484880261,1290503997741, %T A262960 173495416001701,27499205820027021,5075028072491665861, %U A262960 1078923766195953890541,261780612944688782844901,71901410584558939807059021,22195276604290979611365107461,7651037112318147566092161607341 %N A262960 a(n) = sum(stirling2(n,k)*(k+2)!*(k+3)!, k=1..n)/144. %C A262960 It appears that for all n the last digit of a(n) is 1. %F A262960 Representation as a sum of infinite series of special values of hypergeometric functions of type 2F0, in Maple notation: sum(k^n*(k+2)!*(k+3)!*hypergeom([k+3,k+4],[],-1)/k!, k=1..infinity)/144, n=1,2... . %F A262960 a(n) ~ exp(1/2) * (n+2)! * (n+3)! / 144. - _Vaclav Kotesovec_, Oct 05 2015 %p A262960 with(combinat): a:= n-> sum(stirling2(n, k)*(k+2)!*(k+3)!, k=1..n)/144: seq(a(n), n=1..20); %t A262960 Table[Sum[StirlingS2[n, k] (k + 2)! (k + 3)!, {k, n}]/144, {n, 16}] (* _Michael De Vlieger_, Oct 05 2015 *) %Y A262960 Cf. A261833. %K A262960 nonn %O A262960 1,2 %A A262960 _Karol A. Penson_ and Katarzyna Gorska, Oct 05 2015