A074551 a(n) = 3^n + 4^n + 9^n.
3, 16, 106, 820, 6898, 60316, 536266, 4801540, 43118818, 387702316, 3487892026, 31385431060, 282446845138, 2541934531516, 22877065673386, 205892220185380, 1853024526865858, 16677199008675916, 150094704403896346
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..200
- Index entries for linear recurrences with constant coefficients, signature (16,-75,108).
Programs
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Magma
[3^n + 4^n + 9^n: n in [0..30]]; // Vincenzo Librandi, Jun 13 2011
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Mathematica
Table[3^n + 4^n + 9^n, {n, 0, 20}]
Formula
From Mohammad K. Azarian, Dec 28 2008: (Start)
G.f.: 1/(1-3*x) + 1/(1-4*x) + 1/(1-9*x).
E.g.f.: exp(3*x) + exp(4*x) + exp(9*x). (End)
a(n) = 16*a(n-1) - 75*a(n-2) + 108*a(n-3).