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 A103212 #23 Apr 14 2021 11:03:15 %S A103212 1,1,6,93,2380,85405,3956106,224939113,15175702200,1185580310121, %T A103212 105302043709390,10482085765658661,1156062800841590148, %U A103212 139945327558704629221,18449221488652046992914,2631255715262150125502865,403689862107153669227378416,66297391981691913179574751633 %N A103212 a(n) = (1/n) * Sum_{i=0..n-1} C(n,i)*C(n,i+1)*(n-1)^i*n^(n-i) for n>=1, a(0)=1. %H A103212 Andrew Howroyd, <a href="/A103212/b103212.txt">Table of n, a(n) for n = 0..200</a> %F A103212 a(n) = A103209(n, n-1). [corrected by _Vaclav Kotesovec_, Sep 24 2017] %F A103212 a(n) ~ 2^(2*n) * n^(n-3/2) / (sqrt(Pi) * exp(1/2)). - _Vaclav Kotesovec_, Sep 24 2017 %t A103212 Table[HypergeometricPFQ[{-n, n+1}, {2}, -n+1], {n, 0, 20}] (* _Vaclav Kotesovec_, Sep 24 2017 *) %t A103212 Flatten[{1, 1, Table[Sum[Binomial[n, k]*Binomial[n, k+1]*(n-1)^k*n^(n-k), {k, 0, n-1}]/n, {n, 2, 20}]}] (* _Vaclav Kotesovec_, Sep 24 2017 *) %o A103212 (PARI) a(n) = {if(n==0, 1, sum(i=0, n-1, binomial(n,i)*binomial(n,i+1)*(n-1)^i*n^(n-i))/n)} \\ _Andrew Howroyd_, Apr 14 2021 %Y A103212 Cf. A103209, A292798. %K A103212 nonn %O A103212 0,3 %A A103212 _Ralf Stephan_, Jan 27 2005 %E A103212 Prepended a(0)=1 from _Vaclav Kotesovec_, Sep 24 2017 %E A103212 Terms a(15) and beyond from _Andrew Howroyd_, Apr 14 2021