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

0,7

Links

Table of n, a(n) for n=0..35.

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]

Crossrefs

20th row of A068009.

Sequence in context: A212964 A279742 A068042 * A182155 A101586 A178080

Adjacent sequences: A068038 A068039 A068040 * A068042 A068043 A068044

Keyword

nonn

Author

Antti Karttunen, Feb 11 2002

Status

approved