A074534 a(n) = 2^n + 4^n + 7^n.

3, 13, 69, 415, 2673, 17863, 121809, 840055, 5830593, 40616263, 283524849, 1981523095, 13858068513, 96956127463, 678491524689, 4748635284535, 33237225602433, 232647693987463, 1628482317649329, 11399170063804375

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (13,-50,56).

Formula

From Mohammad K. Azarian, Dec 27 2008: (Start)

G.f.: 1/(1-2*x) + 1/(1-4*x) + 1/(1-7*x).

E.g.f.: exp(2*x) + exp(4*x) + exp(7*x). (End)

Mathematica

Table[2^n + 4^n + 7^n, {n, 0, 20}]

Prog

(Magma) [2^n + 4^n + 7^n: n in [0..25]]; // Vincenzo Librandi, Jun 11 2011

Crossrefs

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

Sequence in context: A284718 A284719 A128079 * A153395 A243688 A368708

Adjacent sequences: A074531 A074532 A074533 * A074535 A074536 A074537

Keyword

easy,nonn

Author

Robert G. Wilson v, Aug 23 2002

Status

approved