A074556 a(n) = 3^n + 6^n + 8^n.

3, 17, 109, 755, 5473, 40787, 309529, 2379275, 18463393, 144315107, 1134267049, 8952908795, 70896790513, 562818102227, 4476415458169, 35654571422315, 284296129664833, 2268726602270147, 18115958853570889, 144724548978127835

Offset: 0

Author

Robert G. Wilson v, Aug 23 2002

Keywords

• easy
• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..300
• Index entries for linear recurrences with constant coefficients, signature (17,-90,144).

Crossrefs

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

Programs

Magma

[3^n + 6^n + 8^n: n in [0..20]]; // Vincenzo Librandi, May 20 2011

Mathematica

Table[3^n + 6^n + 8^n, {n, 0, 20}]
LinearRecurrence[{17,-90,144},{3,17,109},21] (* Harvey P. Dale, May 19 2011 *)

Formula

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

G.f.: 1/(1-3*x) + 1/(1-6*x) + 1/(1-8*x).

E.g.f.: e^(3*x) + e^(6*x) + e^(8*x). (End)

a(n) = 17*a(n-1) - 90*a(n-2) + 144*a(n-3); a(0)=3, a(1)=17, a(2)=109. - Harvey P. Dale, May 19 2011