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