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A086328
Number of n X n circulant singular (0,1) matrices over the reals.
3
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
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
Sequence in context: A222821 A363418 A245497 * A095997 A274139 A283995
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