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 A066382 #23 Sep 01 2025 07:49:08
%S A066382 1,2,11,130,2517,68406,2391496,102022810,5130659561,296881218694,
%T A066382 19415908147836,1415538531617772,113796709835547767,
%U A066382 9998149029974754104,952980844872975079232,97930011125976327934826,10791878598088498089377489,1269466214540655412954317894
%N A066382 a(n) = Sum_{k=0..n} binomial(n^2,k).
%H A066382 Harry J. Smith, <a href="/A066382/b066382.txt">Table of n, a(n) for n = 0..100</a>
%F A066382 a(n) = 2^(n^2) - binomial(n^2, n+1)*hypergeom([1, -n^2+n+1], [2+n], -1). - _Vladeta Jovovic_, Jul 08 2003
%F A066382 a(n) ~ exp(n - 1/2) * n^(n - 1/2) / sqrt(2*Pi). - _Vaclav Kotesovec_, Jun 07 2019
%t A066382 Table[Sum[Binomial[n^2, k], {k, 0, n}], {n, 0, 20}] (* _Vincenzo Librandi_, Jun 08 2019 *)
%o A066382 (PARI) { for (n=0, 100, a=0; for (k=0, n, a+=binomial(n^2, k)); write("b066382.txt", n, " ", a) ) } \\ _Harry J. Smith_, Feb 12 2010
%o A066382 (PARI) a(n) = sum(k=0, n, binomial(n^2,k)); \\ _Michel Marcus_, Jun 08 2019
%o A066382 (Magma) [&+[Binomial(n^2, k): k in [0..n]]: n in [0..20]]; // _Vincenzo Librandi_, Jun 08 2019
%Y A066382 Cf. A206849.
%K A066382 nonn,changed
%O A066382 0,2
%A A066382 _N. J. A. Sloane_, Dec 23 2001