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 A293989 #12 Mar 24 2025 22:33:36
%S A293989 1,1,3,22,273,4956,122215,3909228,156878337,7694191648,451507161771,
%T A293989 31157580173160,2493155105671153,228656777880920832,
%U A293989 23802477358410219183,2788676280294791340496,364998736798930722881025,53020798447231578364796928
%N A293989 a(0) = a(1) = 1 and a(n) = n! * [x^n] exp((1/(1-x)^(n-1) - 1)/(n-1)) for n > 1.
%H A293989 Seiichi Manyama, <a href="/A293989/b293989.txt">Table of n, a(n) for n = 0..281</a>
%t A293989 a[0]= a[1]= 1; a[n_]:= n! * SeriesCoefficient[Exp[(1/(1-x)^(n-1) - 1)/(n-1)] ,{x,0,n}]; Array[a,18,0] (* _Stefano Spezia_, Mar 24 2025 *)
%Y A293989 Main diagonal of A291709.
%K A293989 nonn
%O A293989 0,3
%A A293989 _Seiichi Manyama_, Oct 21 2017