A182010 Number of potential group developed cocyclic Hadamard matrices over Z_{(2*n+1)^2} X Z^2_2.

8, 398297088, 913318229998415698350080000, 18602466189203099377637961636627003234293304602017169408, 2304373708652156997616388791182260400495232504872785915397329293966094616677825444346286080000

Offset

0,1

Links

Amiram Eldar, Table of n, a(n) for n = 0..13

A. Baliga and K. J. Horadam, Cocyclic Hadamard matrices over Z_t X Z^2_2, Australas. J. Combin. 11 (1995), 123-134.

Formula

a(n) = 8*A109901(2*n+1)^4 (Baliga, et al., p. 130).

a(n) ~ 2^(16*n^2+16*n+5) / (n^4 * exp(2-2/n) * Pi^2). - Amiram Eldar, Sep 20 2025

Mathematica

a[n_] := 8 * Binomial[(2*n+1)^2, (n+1)*(2*n+1)]^4; Array[a, 5, 0] (* Amiram Eldar, Sep 20 2025 *)

Crossrefs

Cf. A109901.

Sequence in context: A076923 A371646 A076911 * A051269 A004740 A108067

Adjacent sequences: A182007 A182008 A182009 * A182011 A182012 A182013

Keyword

nonn,easy

Author

L. Edson Jeffery, Apr 11 2012

Status

approved