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 A227402 #18 Aug 29 2014 10:40:39
%S A227402 1,1,16,525,24616,1505205,113772114,10253539205,1073769343504,
%T A227402 128165285630637,17177527372642000,2554518029816653175,
%U A227402 417444979902876203656,74358489250362053975095,14340040595865309129453250,2976703788777987140216622005
%N A227402 Number of unimodal functions f:[n]->[n^2].
%H A227402 Alois P. Heinz, <a href="/A227402/b227402.txt">Table of n, a(n) for n = 0..110</a>
%F A227402 a(n) = Sum_{j=0..n^2-1} C(n+2*j-1,2*j), a(0) = 1.
%F A227402 a(n) = A071921(n,n^2).
%F A227402 a(n) ~ 2^(n-3/2) * n^(n-1/2) * exp(n+1/4) / sqrt(Pi). - _Vaclav Kotesovec_, Aug 29 2014
%p A227402 a:= n-> `if`(n=0, 1, add(binomial(n+2*j-1, 2*j), j=0..n^2-1)):
%p A227402 seq(a(n), n=0..20);
%t A227402 Flatten[{1,Table[Sum[Binomial[n+2*j-1, 2*j], {j,0,n^2-1}],{n,1,20}]}] (* _Vaclav Kotesovec_, Aug 29 2014 *)
%Y A227402 Main diagonal of A226031.
%Y A227402 Cf. A071920, A227406.
%K A227402 nonn
%O A227402 0,3
%A A227402 _Alois P. Heinz_, Sep 20 2013