A173736 a(n) = (10^n + 35)/9 for n>0.

5, 15, 115, 1115, 11115, 111115, 1111115, 11111115, 111111115, 1111111115, 11111111115, 111111111115, 1111111111115, 11111111111115, 111111111111115, 1111111111111115, 11111111111111115, 111111111111111115, 1111111111111111115, 11111111111111111115, 111111111111111111115

Offset: 1

Author

Vincenzo Librandi, Feb 23 2010

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A093135.

Programs

Magma

[(10^n+35)/9: n in [1..20]]; // Vincenzo Librandi, Jul 05 2012

Mathematica

CoefficientList[Series[(5-40*x)/((1-x)*(1-10*x)),{x,0,30}],x] (* Vincenzo Librandi, Jul 05 2012 *)

Formula

a(n) = a(n-1) + 10^(n-1) = 10*a(n-1) - 35 with n>0, a(0)=4.

From Vincenzo Librandi, Jul 05 2012: (Start)

G.f.: 5*x*(1-8*x)/((1-x)*(1-10*x)).

a(n) = 11*a(n-1) - 10*a(n-2). (End)

From Elmo R. Oliveira, Jun 18 2025: (Start)

E.g.f.: -4 + exp(x)*(35 + exp(9*x))/9.

a(n) = 5*A093135(n-1). (End)