A226264 Number of additive Z_2 Z_8 codes of a certain type (see Siap-Aydogdu for precise definition).

36, 84, 180, 372, 756, 1524, 3060, 6132, 12276, 24564, 49140, 98292, 196596, 393204, 786420, 1572852, 3145716, 6291444, 12582900, 25165812, 50331636, 100663284, 201326580, 402653172, 805306356, 1610612724, 3221225460, 6442450932, 12884901876, 25769803764

Offset

1,1

Comments

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

Links

Lars Blomberg, Table of n, a(n) for n = 1..100

I. Siap and I. Aydogdu, Counting The Generator Matrices of Z_2 Z_8 Codes, arXiv preprint arXiv:1303.6985 [math.CO], 2013.

Formula

Conjectures from Colin Barker, Jun 14 2017: (Start)

G.f.: 12*x*(3 - 2*x) / ((1 - x)*(1 - 2*x)).

a(n) = 12*(2^(1+n) - 1) for n>0.

a(n) = 3*a(n-1) - 2*a(n-2) for n>2.

(End)

Mathematica

QP = QPochhammer;
a[n_] := 2(6(2^(n+3))^n QP[2^(-n-1), 2, n])/((2^(n+2))^n QP[2^-n, 2, n]);
Array[a, 30] (* Jean-François Alcover, Sep 01 2018 *)

Crossrefs

Cf. A226262, A226263, A226265, A226266, A226267, A226268.

Sequence in context: A084006 A254648 A202330 * A243804 A043183 A039360

Adjacent sequences: A226261 A226262 A226263 * A226265 A226266 A226267

Keyword

nonn

Author

N. J. A. Sloane, Jun 02 2013

Extensions

Terms a(6) and beyond from Lars Blomberg, Jun 14 2017

Status

approved