OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
FORMULA
Euler transform of period 7 sequence [1, 1, -1, 1, -1, -1, 0, ...]. - Michael Somos, Nov 11 2005
G.f.: Product_{k>0} (1-x^(7k-4))(1-x^(7k-2))(1-x^(7k-1))/((1-x^(7k-3))*(1-x^(7k-5))(1-x^(7k-6))). - Michael Somos, Nov 11 2005
PROG
(PARI) {a(n)=if(n<0, 0, polcoeff( prod(k=1, n, (1-x^k)^-kronecker(-7, k), 1+x*O(x^n)), n))} /* Michael Somos, Nov 11 2005 */
CROSSREFS
KEYWORD
sign,look
AUTHOR
N. J. A. Sloane, Nov 09 2005
STATUS
approved