A074552 a(n) = 3^n + 5^n + 7^n.

3, 15, 83, 495, 3107, 20175, 134003, 903855, 6161987, 42326415, 292299923, 2026332015, 14085959267, 98111307855, 684331371443, 4778093436975, 33385561506947, 233393582580495, 1632228682596563, 11417969833962735

Offset: 0

Author

Robert G. Wilson v, Aug 23 2002

Keywords

• easy
• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200
• Index entries for linear recurrences with constant coefficients, signature (15,-71,105).

Crossrefs

Cf. A001550, A001576, A034513, A001579, A074501 - A074580.

Programs

Magma

[3^n + 5^n + 7^n: n in [0..30]]; // Vincenzo Librandi, Jun 13 2011

Mathematica

Table[3^n + 5^n + 7^n, {n, 0, 20}]
LinearRecurrence[{15,-71,105},{3,15,83},20] (* Harvey P. Dale, Jul 16 2020 *)

Formula

From Mohammad K. Azarian, Dec 30 2008: (Start)

G.f.: 1/(1-3*x) + 1/(1-5*x) + 1/(1-7*x).

E.g.f.: exp(3*x) + exp(5*x) + exp(7*x). (End)

a(n) = 15*a(n-1) - 71*a(n-2) + 105*a(n-3).