A074536 a(n) = 2^n + 4^n + 9^n.
3, 15, 101, 801, 6833, 60105, 535601, 4799481, 43112513, 387683145, 3487834001, 31385255961, 282446317793, 2541932945385, 22877060906801, 205892205869241, 1853024483884673, 16677198879666825, 150094704016738001
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..200
- Index entries for linear recurrences with constant coefficients, signature (15,-62,72).
Programs
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Magma
[2^n + 4^n + 9^n: n in [0..25]]; // Vincenzo Librandi, Jun 11 2011
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Mathematica
Table[2^n + 4^n + 9^n, {n, 0, 20}]
Formula
From Mohammad K. Azarian, Dec 27 2008: (Start)
G.f.: 1/(1-2*x) + 1/(1-4*x) + 1/(1-9*x).
E.g.f.: exp(2*x) + exp(4*x) + exp(9*x). (End)