A074577 a(n) = 6^n + 7^n + 8^n.

3, 21, 149, 1071, 7793, 57351, 426449, 3200631, 24221633, 184649031, 1416683249, 10930058391, 84737546273, 659705518311, 5154633748049, 40402118583351, 317529017187713, 2501356987117191, 19744372064060849, 156123443001239511

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..300

Index entries for linear recurrences with constant coefficients, signature (21,-146,336).

Formula

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

G.f.: 1/(1-6*x) + 1/(1-7*x) + 1/(1-8*x).

E.g.f.: e^(6*x) + e^(7*x) + e^(8*x). (End)

a(n) = 21*a(n-1) - 146*a(n-2) + 336*a(n-3); a(0)=3, a(1)=21, a(2)=149. - Harvey P. Dale, Dec 25 2011

Mathematica

Table[6^n + 7^n + 8^n, {n, 0, 19}]
LinearRecurrence[{21, -146, 336}, {3, 21, 149}, 20] (* Harvey P. Dale, Dec 25 2011 *)

Prog

(Magma) [6^n + 7^n + 8^n: n in [0..20]]; // Vincenzo Librandi, May 20 2011

Crossrefs

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

Sequence in context: A037649 A037768 A037656 * A007566 A183412 A155627

Adjacent sequences: A074574 A074575 A074576 * A074578 A074579 A074580

Keyword

easy,nonn

Author

Robert G. Wilson v, Aug 23 2002

Status

approved