A086328 Number of n X n circulant singular (0,1) matrices over the reals.

1, 2, 2, 8, 2, 28, 2, 96, 62, 284, 2, 1504, 2, 3560, 2738, 16896, 2, 67636, 2, 235736, 109334, 707480, 2, 4376848, 206282, 10408792, 5417630, 48753784, 2, 212560504, 2, 739236864, 278770214, 2333737292, 133401818, 13837799440, 2

Offset

1,2

Comments

a(2*n+1) = A144926(2*n+1), n>0. a(2*p) = 2^p + binomial(2*p,p) if p is an odd prime, cf. A144926. - Vladeta Jovovic, Oct 02 2008

Links

W. F. Lunnon, Table of n, a(n) for n = 1..39

W. F. Lunnon, C program for A144926 and A086328

Formula

a(n) = 2^n - A086323(n).

For a prime p, a(p) = 2 and the two circulants are those with all rows equal (0, 0, 0, ..., 0) or all rows equal (1, 1, 1, ..., 1).

Crossrefs

Cf. A086323, A086324.

Sequence in context: A222821 A363418 A245497 * A095997 A274139 A283995

Adjacent sequences: A086325 A086326 A086327 * A086329 A086330 A086331

Keyword

nonn

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 30 2003

Extensions

More terms from Fred Lunnon, Oct 28 2008

a(0) removed, a(1) corrected by Max Alekseyev, Sep 25 2009

Status

approved