A068036 Number of subsets of {1,2,3,...,n} that sum to 0 mod 15.

1, 1, 1, 1, 1, 2, 5, 9, 18, 36, 70, 138, 276, 548, 1096, 2192, 4374, 8744, 17486, 34958, 69916, 139830, 279630, 559260, 1118520, 2236988, 4473964, 8947920, 17895736, 35791472, 71582944, 143165660, 286331296, 572662588, 1145324764, 2290649528

Offset: 0

Author

Antti Karttunen, Feb 11 2002

Keywords

• nonn

Crossrefs

15th row of A068009.

Formula

Empirical G.f.: -(8*x^23 +4*x^21 -8*x^20 +4*x^19 -4*x^18 +2*x^17 -4*x^16 +2*x^15 -8*x^14 +2*x^12 +8*x^11 +4*x^10 +4*x^9 -6*x^8 -3*x^7 -5*x^6 -x^4 +3*x^3 +x^2 +x -1) / ((2*x-1) * (2*x^3-1) * (2*x^5-1) * (2*x^15-1)). - Colin Barker, Dec 22 2012