A081657 2*7^n-3^n.

1, 11, 89, 659, 4721, 33371, 234569, 1644899, 11523041, 80687531, 564891449, 3954476339, 27682042961, 193776426491, 1356441362729, 9495108670979, 66465818092481, 465260898834251, 3256826808400409, 22797789208484819

Offset: 0

Author

Paul Barry, Mar 26 2003

Keywords

• easy
• nonn

Comments

Binomial transform of A081656.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (10,-21).

Programs

Magma

[2*7^n-3^n: n in [0..30]]; // Vincenzo Librandi, Dec 05 2012

Mathematica

CoefficientList[Series[(1 + x) / ((1 - 7 x) (1 - 3 x)), {x, 0, 40}], x] (* Vincenzo Librandi, Aug 10 2013 *)

Formula

G.f.: (1+x)/((1-7*x)*(1-3*x)).

E.g.f. 2*exp(7*x)-exp(3*x).

a(0)=0, a(1)=11; for n>1, a(n) = 10*a(n-1) -21*a(n-2). - Vincenzo Librandi Aug 10 2013