A155656 a(n) = 9^n + 7^n - 1.

1, 15, 129, 1071, 8961, 75855, 649089, 5606511, 48811521, 427774095, 3769259649, 33358386351, 296270823681, 2638754838735, 23555015527809, 210638693604591, 1886253119421441, 16909812213653775, 151723048894909569, 1362250612858365231, 12237457725354540801

Offset: 0

Author

Mohammad K. Azarian, Jan 31 2009

Keywords

• nonn
• easy

Links

• Paolo Xausa, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (17,-79,63).

Crossrefs

Cf. A155638, A155639, A155640, A155641, A155642, A155643, A155644, A155645, A155646, A155647, A155648, A155649, A155650, A155651, A155652, A155653, A155654, A155655.

Programs

Mathematica

Table[9^n + 7^n - 1, {n, 0, 25}] (* Paolo Xausa, Jul 28 2024 *)

PARI

a(n)=9^n+7^n-1 \\ Charles R Greathouse IV, Jun 11 2015

Formula

G.f.: 1/(1-9*x) + 1/(1-7*x) - 1/(1-x).

E.g.f.: e^(9*x) + e^(7*x) - e^x.

a(n) = 16*a(n-1)-63*a(n-2)-48 with a(0) = 1, a(1) = 15. - Vincenzo Librandi, Jul 21 2010