A198644 a(n) = 8*3^n - 1.

7, 23, 71, 215, 647, 1943, 5831, 17495, 52487, 157463, 472391, 1417175, 4251527, 12754583, 38263751, 114791255, 344373767, 1033121303, 3099363911, 9298091735, 27894275207, 83682825623, 251048476871, 753145430615, 2259436291847, 6778308875543, 20334926626631, 61004779879895

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4,-3).

Formula

a(n) = 3*a(n-1) + 2, a(0)=7.

G.f.: (7-5*x)/((3*x-1)*(x-1)). - R. J. Mathar, Oct 30 2011

From Elmo R. Oliveira, May 07 2025: (Start)

E.g.f.: exp(x)*(8*exp(2*x) - 1).

a(n) = 4*a(n-1) - 3*a(n-2).

a(n) = A199111(n) - 2. (End)

Mathematica

8*3^Range[0, 30]-1 (* or *) LinearRecurrence[{4, -3}, {7, 23}, 30] (* Harvey P. Dale, Jun 16 2024 *)

Prog

(Magma) [8*3^n-1: n in [0..30]];

Crossrefs

Cf. A199111.

Sequence in context: A005342 A139852 A141194 * A045535 A001984 A147972

Adjacent sequences: A198641 A198642 A198643 * A198645 A198646 A198647

Keyword

nonn,easy

Author

Vincenzo Librandi, Oct 28 2011

Status

approved