A350054 a(n) = (4^(3*n+2) - 7)/9.

113, 7281, 466033, 29826161, 1908874353, 122167958641, 7818749353073, 500399958596721, 32025597350190193, 2049638230412172401, 131176846746379033713, 8395318191768258157681, 537300364273168522091633, 34387223313482785413864561

Offset: 1

Author

Wolfdieter Lang, Jan 20 2022

Keywords

• nonn
• easy

Comments

Bisection of A350053, namely the even part. The odd part is given in A228871.

Links

• Winston de Greef, Table of n, a(n) for n = 1..551
• Index entries for linear recurrences with constant coefficients, signature (65,-64).

Crossrefs

Cf. A133853, A228871, A350053.

Programs

Mathematica

Table[(4^(3*n + 2) - 7)/9, {n, 1, 14}] (* Amiram Eldar, Jan 21 2022 *)

PARI

a(n) = (4^(3*n+2) - 7)/9 \\ Winston de Greef, Jan 27 2024

Formula

a(n) = (2^(6*n+4) - 7)/9, n >= 1.

G.f.: x*(113 - 64*x)/((1 - x)*(1 - 64*x)).

a(n) = 112*A133853(n) + 1. - Hugo Pfoertner, Jan 21 2022