A226267 - OEIS

%I #22 Nov 05 2025 15:22:24

%S 2352,9721600,449914060800,280154359021436928,

%T 2560999281742478158331904,358821757256355942900943762227200,

%U 787296929540087707656924853902883002777600,27343461806425897751473875699316284363491645025419264

%N Number of additive Z_2 Z_8 codes of a certain type (see Siap-Aydogdu for precise definition).

%C N2×8(r+2, 2r+1; r, 0, 1, r) r>=1. (Siap-Aydogdu Table 1)

%H Lars Blomberg, <a href="/A226267/b226267.txt">Table of n, a(n) for n = 1..30</a>

%H I. Siap and I. Aydogdu, <a href="https://arxiv.org/abs/1303.6985">Counting The Generator Matrices of Z_2 Z_8 Codes</a>, arXiv preprint arXiv:1303.6985 [math.CO], 2013.

%t QP = QPochhammer;

%t a[n_] := (2^(2n+1)(8^(n+1))^n (2^(2n+1)-1) QP[2^(-2-n), 2, n] QP[4^-n, 2, n])/((2^(n+1))^n QP[2^(-n), 2, n]^2 2^(n-1));

%t Array[a, 8] (* _Jean-François Alcover_, Sep 01 2018 *)

%Y Cf. A226262, A226263, A226264, A226265, A226266, A226268.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Jun 02 2013

%E Terms a(4) and beyond from _Lars Blomberg_, Jun 14 2017