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

Author

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

Keywords

• nonn

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

Crossrefs

Cf. A086323, A086324.

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).

Extensions

More terms from Fred Lunnon, Oct 28 2008

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