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 A109901 #33 Sep 03 2024 08:24:49
%S A109901 1,1,4,84,8008,3268760,5567902560,39049918716424,1118770292985239888,
%T A109901 130276394656770614583240,61448471214136179596720592960,
%U A109901 117118180539414377821494470432491764,900390992257782351906806257139068209113040,27883369051325994219981405855549095749234579210080
%N A109901 a(n) = binomial(n^2, n*(n+1)/2).
%C A109901 8*a(2*n+1)^4 = A182010(n) = number of potential group developed cocyclic Hadamard matrices over (the group) Z_{(2*n+1)^2} X Z^2_2 [Baliga, et al., p. 130]. - _L. Edson Jeffery_, Apr 10 2012
%H A109901 Andrew Howroyd, <a href="/A109901/b109901.txt">Table of n, a(n) for n = 0..50</a>
%H A109901 A. Baliga and K. J. Horadam, <a href="http://ajc.maths.uq.edu.au/pdf/11/ocr-ajc-v11-p123.pdf">Cocyclic Hadamard matrices over Z_t X Z^2_2</a>, Australas. J. Combin. 11(1995), 123-134.
%F A109901 a(n) = C(n^2, n*(n+1)/2) = (n^2!)/((n(n+1)/2)!*(n(n-1)/2)!).
%F A109901 a(n) = C(n^2, n*(n-1)/2).
%e A109901 a(6) = 36!/(21!*15!) = 5567902560.
%p A109901 seq(binomial(n^2,n*(n+1)/2),n=0..12); # _Emeric Deutsch_, Jul 16 2005
%t A109901 Table[Binomial[n^2,(n(n+1))/2],{n,20}] (* _Harvey P. Dale_, Jun 04 2011 *)
%o A109901 (PARI) a(n)=binomial(n^2,n*(n+1)/2)
%Y A109901 Cf. variants: A014062 (C(n^2,n*(n-1))), A135757 (C(n*(n+1),n*(n+1)/2)).
%Y A109901 Cf. A182010.
%K A109901 easy,nonn
%O A109901 0,3
%A A109901 _Amarnath Murthy_, Jul 14 2005
%E A109901 More terms from _Emeric Deutsch_, Jul 16 2005
%E A109901 Offset changed to 0 (with a(0)=1), and name changed slightly by _Paul D. Hanna_, Jun 24 2011
%E A109901 Terms a(12) and beyond from _Andrew Howroyd_, Nov 09 2019