A177108 a(n) = 4*(10^n-3).

28, 388, 3988, 39988, 399988, 3999988, 39999988, 399999988, 3999999988, 39999999988, 399999999988, 3999999999988, 39999999999988, 399999999999988, 3999999999999988, 39999999999999988, 399999999999999988

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

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

Formula

G.f.: 4*x*(7+20*x) / ( (10*x-1)*(x-1) ). a(n)=4*A173833(n). - R. J. Mathar, Jan 06 2011

a(n) = a(n-1) +36*10^(n-1) = 10*a(n-1) +108 = 11*a(n-1) -10*a(n-2). - Vincenzo Librandi, Jul 15 2012

Mathematica

CoefficientList[Series[4*(7+20*x)/((10*x-1)*(x-1)), {x, 0, 40}], x] (* Vincenzo Librandi, Jul 15 2012 *)
4(10^Range[20]-3) (* or *) LinearRecurrence[{11, -10}, {28, 388}, 20] (* Harvey P. Dale, Sep 25 2012 *)

Prog

(Magma) [4*(10^n-3): n in [1..20]]; // Vincenzo Librandi, Jul 15 2012

Crossrefs

Sequence in context: A077507 A130608 A331353 * A283637 A126921 A035709

Adjacent sequences: A177105 A177106 A177107 * A177109 A177110 A177111

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 15 2010

Status

approved