A124281 Expansion of 1/(1-x-2*x^2+2*x^3-2*x^4).

1, 1, 3, 3, 9, 11, 29, 39, 93, 135, 301, 463, 981, 1575, 3213, 5327, 10565, 17943, 34845, 60255, 115189, 201895, 381453, 675375, 1264869, 2256503, 4198397, 7532415, 13945941, 25126983, 46350829, 83777743, 154117317, 279225111

Offset: 0

Author

Paul Barry, Oct 24 2006

Keywords

• easy
• nonn

Links

• Index entries for linear recurrences with constant coefficients, signature (1,2,-2,2).

Crossrefs

Cf. A124280.

Formula

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