A113240 Expansion of (1/(1-x))*sum(k>=2,x^k/(1-2x^k)).

1, 2, 5, 6, 13, 14, 25, 30, 49, 50, 97, 98, 165, 186, 325, 326, 621, 622, 1161, 1230, 2257, 2258, 4481, 4498, 8597, 8858, 17125, 17126, 34077, 34078, 66985, 68014, 133553, 133634, 267057, 267058, 529205, 533306, 1058261, 1058262, 2115133

Offset: 0

Author

Paul Barry, Oct 19 2005

Keywords

• easy
• nonn

Crossrefs

Cf. A002541.

Formula

a(n)=sum{k=0..floor(n/2), floor((n-k+1)/(k+1))*2^k}.