A074539 a(n) = 2^n + 5^n + 8^n.
3, 15, 93, 645, 4737, 35925, 277833, 2175405, 17168097, 136171365, 1083508473, 8638764765, 68963621457, 550976525205, 4404150043113, 35214889699725, 281627564666817, 2252562753269445, 18018213207009753, 144134261562708285
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..200
- D. Suprijanto, I. W. Suwarno, Observation on Sums of Powers of Integers Divisible by 3k-1, Applied Mathematical Sciences, Vol. 8, 2014, no. 45, pp. 2211-2217.
- Index entries for linear recurrences with constant coefficients, signature (15,-66,80).
Programs
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Magma
[2^n + 5^n + 8^n: n in [0..25]]; // Vincenzo Librandi, Jun 11 2011
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Mathematica
Table[2^n + 5^n + 8^n, {n, 0, 20}]
Formula
From Mohammad K. Azarian, Dec 27 2008: (Start)
G.f.: 1/(1-2*x) + 1/(1-5*x) + 1/(1-8*x).
E.g.f.: exp(2*x) + exp(5*x) + exp(8*x). (End)