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 A094955 #12 Nov 05 2016 04:09:32
%S A094955 1,2,11,91,985,13201,211303,3936808,83739041,2003229469,53252096051,
%T A094955 1557702562417,49731172316281,1720974414781454,64174041067789199,
%U A094955 2565470565551429551,109461497917277584513,4965206236292285024041
%N A094955 Main diagonal of array A094954.
%F A094955 a(n) = y(n,n), where y(m+1,n)=n*y(m,n)-y(m-1,n), with y(0,n)=y(1,n)=y(2,n)=1 for all n. - _Benedict W. J. Irwin_, Nov 03 2016
%F A094955 a(n) ~ exp(1) * n^(n-1). - _Vaclav Kotesovec_, Nov 05 2016
%t A094955 Table[DifferenceRoot[Function[{y, m}, {y[1 + m] == n*y[m] - y[m - 1], y[0] == 1, y[1] == 1, y[2] == 1}]][n], {n, 2, 20}] (* _Benedict W. J. Irwin_, Nov 03 2016 *)
%Y A094955 Cf. A094954.
%K A094955 nonn
%O A094955 1,2
%A A094955 _Ralf Stephan_, May 31 2004