A173802 a(n) = (5*10^n - 23)/9.

3, 53, 553, 5553, 55553, 555553, 5555553, 55555553, 555555553, 5555555553, 55555555553, 555555555553, 5555555555553, 55555555555553, 555555555555553, 5555555555555553, 55555555555555553, 555555555555555553, 5555555555555555553, 55555555555555555553, 555555555555555555553

Offset: 1

Author

Vincenzo Librandi, Feb 25 2010

Keywords

• nonn
• easy

Examples

			For n=2, a(2) = 10*3 + 23 = 53.
For n=3, a(3) = 10*53 + 23 = 553.
For n=4, a(4) = 10*553 + 23 = 5553.
		

Links

• Index entries for linear recurrences with constant coefficients, signature (11,-10).

Crossrefs

Cf. A093164.

Programs

Mathematica

Rest[CoefficientList[Series[x*(3 + 20*x)/((10*x - 1)*(x - 1)), {x,0,50}], x]] (* G. C. Greubel, May 06 2017 *)
Table[FromDigits[PadLeft[{3},n,5]],{n,20}] (* or *) LinearRecurrence[ {11,-10},{3,53},20] (* Harvey P. Dale, May 27 2018 *)

PARI

x=x+O('x^50); Vec(x*(3+20*x)/((10*x-1)*(x-1))) \\ G. C. Greubel, May 06 2017

Formula

a(n) = 10*a(n-1) + 23 for n > 1.

G.f.: x*(3+20*x)/((10*x-1)*(x-1)). - R. J. Mathar, Aug 24 2011

From Elmo R. Oliveira, Sep 09 2024: (Start)

E.g.f.: exp(x)*(5*exp(9*x) - 23)/9.

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