A177074 3*(10^n-5).

15, 285, 2985, 29985, 299985, 2999985, 29999985, 299999985, 2999999985, 29999999985, 299999999985, 2999999999985, 29999999999985, 299999999999985, 2999999999999985, 29999999999999985, 299999999999999985

Offset: 1

Author

Vincenzo Librandi

Keywords

• nonn
• easy

Comments

Apparently 15 times the entries in A067272. - R. J. Mathar, Aug 24 2011

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..100
• Index entries for linear recurrences with constant coefficients, signature (11,-10).

Programs

Magma

[3*(10^n-5): n in [1..20]]; // Vincenzo Librandi, Apr 26 2014

Mathematica

Table[3*(10^n-5),{n,20}] (* or *) LinearRecurrence[{11,-10},{15,285},20] (* Harvey P. Dale, Apr 25 2014 *)
CoefficientList[Series[15 (1 + 8 x)/((10 x - 1) (x - 1)), {x, 0, 40}], x] (* Vincenzo Librandi, Apr 26 2014 *)

Formula

G.f. 15*x*(1+8*x) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Aug 24 2011

a(n) = 11*a(n-1) - 10*a(n-2), n>1. - Vincenzo Librandi, Apr 26 2014