A074557 3^n + 6^n + 9^n.
3, 18, 126, 972, 7938, 67068, 578826, 5065092, 44732898, 397517868, 3547309626, 31744033812, 284606850258, 2554928116668, 22955161402026, 206361331428132, 1855841341806018, 16694108488251468, 150196195641088026
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (18,-99,162).
Programs
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Magma
[3^n + 6^n + 9^n: n in [0..20]]; // Vincenzo Librandi, Aug 24 2011
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Mathematica
Table[3^n + 6^n + 9^n, {n, 0, 20}]
Formula
G.f.: 1/(1-3*x)+1/(1-6*x)+1/(1-9*x). E.g.f.: exp(3*x)+exp(6*x)+exp(9*x). [From Mohammad K. Azarian, Dec 30 2008]