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A155656
a(n) = 9^n + 7^n - 1.
19
1, 15, 129, 1071, 8961, 75855, 649089, 5606511, 48811521, 427774095, 3769259649, 33358386351, 296270823681, 2638754838735, 23555015527809, 210638693604591, 1886253119421441, 16909812213653775, 151723048894909569, 1362250612858365231, 12237457725354540801
OFFSET
0,2
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
MATHEMATICA
Table[9^n + 7^n - 1, {n, 0, 25}] (* Paolo Xausa, Jul 28 2024 *)
PROG
(PARI) a(n)=9^n+7^n-1 \\ Charles R Greathouse IV, Jun 11 2015
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, Jan 31 2009
STATUS
approved