A159035 a(0)=1=a(1), a(2)=2, a(3)=5; thereafter a(n+3)=4*a(n+2)-4*a(n+1)+2*a(n) for n>=1.

1, 1, 2, 5, 14, 40, 114, 324, 920, 2612, 7416, 21056, 59784, 169744, 481952, 1368400, 3885280, 11031424, 31321376, 88930368, 252498816, 716916544, 2035531648, 5779458048, 16409538688, 46591385856, 132286304768, 375598753024

Offset: 0

Author

Richard Choulet, Apr 03 2009

Keywords

• easy
• nonn

Comments

A117189 prefixed by an initial 1; essentially a duplicate. - N. J. A. Sloane and R. J. Mathar, Apr 07 2009

Formula

G.f.: f(z)=((1-3*z+2*z^2-z^3)/(1-4*z+4*z^2-2*z^3))