OFFSET
1,3
COMMENTS
Determinant of a symmetric polynomial evaluated at x = 1 that starts:
{{1, 1, 1, 1, 1},
{1, -1 + x, 1, -1 + x, 1},
{1, 1, -2 + x, 1, 1},
{1, -1 + x, 1, -1, 1},
{1, 1, 1, 1, -4 + x}}. - Mats Granvik, Jul 22 2012
FORMULA
a(n+1)/a(n) = A023900(n+1) the reciprocity balance of n+1.
a(n) = Product_{i=1..A000720(n)} (1-A000040(i))^floor(n/A000040(i)). - Enrique Pérez Herrero, Jul 12 2012
MATHEMATICA
Clear[nn, t, n, k, M, x]; nnn = 27; a = Range[nnn]*0; Do[nn = ii; t[n_, 1] = 1; t[1, k_] = 1; t[n_, k_] := t[n, k] = If[n < k, If[And[n > 1, k > 1], x - Sum[t[k - i, n], {i, 1, n - 1}], 0], If[And[n > 1, k > 1], x - Sum[t[n - i, k], {i, 1, k - 1}], 0]]; x = 1; M = Table[Table[t[n, k], {k, 1, nn}], {n, 1, nn}]; a[[ii]] = Det[M], {ii, 1, nnn}]; a (* Mats Granvik, Jul 22 2012 *)
PROG
(PARI) a(n)=matdet(matrix(n, n, i, j, i/gcd(i, j)))
CROSSREFS
KEYWORD
sign
AUTHOR
Benoit Cloitre, Aug 19 2003
STATUS
approved