0,2
a(n) = A000302(n) - A047653(n) = (A004171(n) - A000980(n)) / 2.
Ray Chandler, Table of n, a(n) for n = 0..1660 (terms < 10^1000)
a(1) = #{{0,1}, {1}} = 2;
a(2) = #{{-2,0,1,2}, {-2,1,2}, {-1,0,1,2}, {-1,0,2}, {-1,1,2}, {-1,2}, {0,1}, {0,1,2}, {0,2}, {1}, {1,2}, {2}} = 12.
(Haskell)
import Data.List (subsequences)
a181765 n = length [xs | xs <- subsequences [-n..n], sum xs > 0]
-- Reinhard Zumkeller, Feb 22 2012, Nov 13 2010
Sequence in context: A212697 A111642 A145766 * A198150 A122676 A038175
Adjacent sequences: A181762 A181763 A181764 * A181766 A181767 A181768
nonn
Reinhard Zumkeller
approved
