A110593 a(1) = 3, a(n+1) = 2*(3^n).

3, 6, 18, 54, 162, 486, 1458, 4374, 13122, 39366, 118098, 354294, 1062882, 3188646, 9565938, 28697814, 86093442, 258280326, 774840978, 2324522934, 6973568802, 20920706406, 62762119218, 188286357654, 564859072962, 1694577218886

Offset: 1

Author

Jonathan Vos Post, Jul 29 2005

Keywords

• easy
• less
• nonn

Comments

Same as A025192 for n > 1. - Georg Fischer, Oct 21 2018

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (3).

Crossrefs

Cf. A000244, A025192, A081604.

Programs

Mathematica

Rest[CoefficientList[Series[3 x + 6 x^2/(1 - 3 x), {x, 0, 50}], x]] (* G. C. Greubel, Sep 01 2017 *)
Join[{3},NestList[3#&,6,30]] (* Harvey P. Dale, Aug 14 2024 *)

PARI

x='x+O('x^50); Vec(3*x + 6*x^2/(1-3*x)) \\ G. C. Greubel, Sep 01 2017

Formula

a(n) = A008776(n-1) for n>1. - R. J. Mathar, Apr 24 2007

G.f.: 3*x + 6*x^2/(1-3*x). - R. J. Mathar, Nov 18 2007