OFFSET
1,2
COMMENTS
Note that if the rows are rotated left instead of right, the sign of the terms for which n = 0 or 3 (mod 4) is reversed. The n eigenvalues of these circulant matrices lie on the circle of radius 2(2^n - 1)/3 centered at x = (2^n - 1)/3, y = 0. This sequence can be generalized to bases other than 2 and similar results are true.
REFERENCES
Richard Bellman, Introduction to Matrix Analysis, Second Edition, SIAM, 1970, pp. 242-3.
Philip J. Davis, Circulant Matrices, Second Edition, Chelsea, 1994.
LINKS
Eric Weisstein's World of Mathematics, Circulant Matrix
FORMULA
a(n) = (-2^n + 1)^(n-1).
See formulas in A180602, an unsigned version of this sequence with offset 0. [Paul D. Hanna, Sep 11 2010]
EXAMPLE
a(3) = determinant of the matrix ((1,2,4),(4,1,2),(2,4,1)) = 49. [Corrected by T. D. Noe, Jan 22 2008]
MAPLE
restart:with (combinat):a:=n->mul(-stirling2(n, 2), j=3..n): seq(a(n), n=2..19); # Zerinvary Lajos, Jan 01 2009
MATHEMATICA
Table[x=2^Range[0, n-1]; m=Table[RotateRight[x, i-1], {i, n}]; Det[m], {n, 12}]
CROSSREFS
Cf. A048954 (circulant of binomial coefficients), A052182 (circulant of natural numbers), A066933 (circulant of prime numbers).
Cf. A180602 (unsigned, offset 0). [Paul D. Hanna, Sep 11 2010]
KEYWORD
easy,sign
AUTHOR
T. D. Noe, Jul 21 2003
STATUS
approved