A068041 Number of subsets of {1,2,3,...,n} that sum to 0 mod 20.

1, 1, 1, 1, 1, 1, 2, 6, 14, 26, 52, 103, 205, 410, 820, 1640, 3278, 6554, 13108, 26216, 52432, 104860, 209716, 419432, 838864, 1677728, 3355448, 6710888, 13421776, 26843552, 53687104, 107374192, 214748368, 429496736, 858993472, 1717986944

Offset: 0

Author

Antti Karttunen, Feb 11 2002

Keywords

• nonn

Crossrefs

20th row of A068009.

Formula

Empirical G.f.: (x-1)^2*(4*x^12+4*x^11-x^10-7*x^9-11*x^8-15*x^7-15*x^6-11*x^5-5*x^4-2*x^3+x+1) / ((2*x-1)*(2*x^5-1)). [Colin Barker, Dec 22 2012]