A198765 7*5^n-1.

6, 34, 174, 874, 4374, 21874, 109374, 546874, 2734374, 13671874, 68359374, 341796874, 1708984374, 8544921874, 42724609374, 213623046874, 1068115234374, 5340576171874, 26702880859374, 133514404296874

Offset: 0

Author

Vincenzo Librandi, Oct 30 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 (6,-5).

Crossrefs

Cf. A024049, A057651, A081655.

Programs

Magma

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

Mathematica

CoefficientList[Series[2*(3 - x)/(1 - 6*x + 5*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)
7 * 5^Range[0, 19] - 1 (* Alonso del Arte, Dec 05 2013 *)

Formula

a(n) = 5*a(n-1) + 4.

a(n) = 6*a(n-1) - 5*a(n-2), n > 1.

G.f.: 2*(3 - x)/(1 - 6*x + 5*x^2). - Vincenzo Librandi, Jan 04 2013