A025796 Expansion of 1/((1-x^2)(1-x^3)(1-x^6)).

1, 0, 1, 1, 1, 1, 3, 1, 3, 3, 3, 3, 6, 3, 6, 6, 6, 6, 10, 6, 10, 10, 10, 10, 15, 10, 15, 15, 15, 15, 21, 15, 21, 21, 21, 21, 28, 21, 28, 28, 28, 28, 36, 28, 36, 36, 36, 36, 45, 36, 45, 45, 45, 45, 55, 45, 55, 55, 55, 55, 66

Offset

0,7

Links

Table of n, a(n) for n=0..60.

Index entries for linear recurrences with constant coefficients, signature (0,1,1,0,-1,1,0,-1,-1,0,1).

Formula

a(6n) = a(6n+2) = a(6n+3) = a(6n+4) = a(6n+5) = n*(n+1)/2. a(6n+1) = (n-1)*n/2. - Franklin T. Adams-Watters, Oct 27 2014

Prog

(PARI) a(n)=(n^2+(4*((n+2)%3)+7+3*(-1)^n)*n+57+33*(-1)^n/2)\72 \\ Tani Akinari, Oct 27 2014

Crossrefs

Cf. A024163.

Sequence in context: A068074 A063195 A334070 * A024163 A029155 A042951

Adjacent sequences: A025793 A025794 A025795 * A025797 A025798 A025799

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved