A198687 5*7^n-1.

4, 34, 244, 1714, 12004, 84034, 588244, 4117714, 28824004, 201768034, 1412376244, 9886633714, 69206436004, 484445052034, 3391115364244, 23737807549714, 166164652848004, 1163152569936034, 8142067989552244, 56994475926865714

Offset: 0

Author

Vincenzo Librandi, Oct 29 2011

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (8,-7).

Crossrefs

Cf. A048473, A081655, A198480, A198647.

Programs

Magma

[5*7^n-1: n in [0..30]]

Mathematica

CoefficientList[Series[(4+2*x)/((1-x)*(1-7*x)),{x,0,40}],x] (* Vincenzo Librandi, Jul 06 2012 *)
LinearRecurrence[{8,-7},{4,34},20] (* Harvey P. Dale, Jul 23 2024 *)

Formula

a(n) = 7*a(n-1)+6 = 8*a(n-1)-7*a(n-2), n>1.

G.f.:(4+2*x)/((1-x)*(1-7*x)). - Vincenzo Librandi, Jul 06 2012