A087448 3^(n-1)(n+3)/2-(n-1)/2.

1, 2, 7, 26, 93, 322, 1091, 3642, 12025, 39362, 127935, 413338, 1328597, 4251522, 13551739, 43046714, 136314609, 430467202, 1355971703, 4261625370, 13366006861, 41841412802, 130754415027, 407953774906, 1270932914153

Offset: 0

Author

Paul Barry, Sep 05 2003

Keywords

• easy
• nonn

Comments

Binomial transform of A087447. Second binomial transform of 1,0,3,0,5,0,7,... (A005408).

Links

• Index entries for linear recurrences with constant coefficients, signature (8,-22,24,-9).

Formula

G.f.: (1-2*x)*(1-4*x+5*x^2)/((1-x)^2*(1-3*x)^2). [Colin Barker, Mar 18 2012]