OFFSET
0,4
LINKS
Eric Weisstein's World of Mathematics, Circulant Matrix.
FORMULA
Contribution from Missouri State University Problem-Solving Group (MSUPSG(AT)MissouriState.edu), May 05 2010: (Start)
a(n) = (-1)^(n-1)*(n - 1)^2*n^(n-2)*(n^(2n) - b(n)^n - c(n)^n + (n^2 - 3*n + 3)^n)/24 for n > 0, where b(n) = (2*n^2 - 3*n - 3 + sqrt(15*n^2 - 18*n - 9)*I)/2, c(n) = (2*n^2 - 3*n - 3 - sqrt(15*n^2 - 18*n - 9)*I)/2, and I the imaginary unit. (End)
EXAMPLE
a(2) = -1 because of the determinant -1 =
| 0, 1 |
| 1, 0 |.
a(3) = 513 = determinant
|0,1,8|
|8,0,1|
|1,8,0|.
a(6) = 22051842087895137 = determinant
|0,1,8,27,64,125,216|
|216,0,1,8,27,64,125|
|125,216,0,1,8,27,64|
|64,125,216,0,1,8,27|
|27,64,125,216,0,1,8|
|8,27,64,125,216,0,1|
|1,8,27,64,125,216,0|.
MAPLE
a:= n-> LinearAlgebra[Determinant](Matrix(n, shape=Circulant[[i^3$i=0..n-1]])):
seq(a(n), n=0..14); # Alois P. Heinz, Feb 21 2026
MATHEMATICA
Join[{1}, Table[Det[Table[RotateRight[Range[0, i-1]^3, n], {n, 0, i-1}]], {i, 13}]] (* Harvey P. Dale, Oct 22 2012 *)
b[n_]:=(2*n^2-3*n-3+Sqrt[15n^2-18n-9]I)/2; c[n_]:=(2*n^2-3*n-3-Sqrt[15n^2-18n-9]I)/2; a[0]=1; a[n_]:=(-1)^(n-1)*(n-1)^2*n^(n-2)*(n^(2n)-b[n]^n-c[n]^n+(n^2-3n+3)^n)/24; Simplify[Array[a, 14, 0]] (* Stefano Spezia, Feb 21 2026 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Jonathan Vos Post, May 20 2006
EXTENSIONS
More terms from Harvey P. Dale, Oct 22 2012
a(0)=1 prepended by Alois P. Heinz, Feb 21 2026
STATUS
approved
