A074559 a(n) = 3^n + 7^n + 9^n.
3, 19, 139, 1099, 9043, 76099, 649819, 5608699, 48818083, 427793779, 3769318699, 33358563499, 296271355123, 2638756433059, 23555020310779, 210638707953499, 1886253162468163, 16909812342793939, 151723049282330059
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (19,-111,189).
Programs
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Magma
[3^n + 7^n + 9^n: n in [0..20]]; // Vincenzo Librandi, Aug 24 2011
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Mathematica
Table[3^n + 7^n + 9^n, {n, 0, 20}]
Formula
From Mohammad K. Azarian, Dec 30 2008: (Start)
G.f.: 1/(1-3*x) + 1/(1-7*x) + 1/(1-9*x).
E.g.f.: exp(3*x) + exp(7*x) + exp(9*x). (End)
a(n) = 19*a(n-1) - 111*a(n-2) + 189*a(n-3). - Wesley Ivan Hurt, Apr 11 2023