A014926 a(1)=1, a(n) = n*11^(n-1) + a(n-1).

1, 23, 386, 5710, 78915, 1045221, 13446148, 169343516, 2098573445, 25678050355, 310989720966, 3734729768298, 44534298665671, 527852268680705, 6224099772429320, 73060070483079736

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..900

Index entries for linear recurrences with constant coefficients, signature (23,-143,121).

Formula

a(1)=1, a(2)=23, a(n) = 22*a(n-1) - 121*a(n-2) + 1. - Vincenzo Librandi, Oct 23 2012

G.f.: x/((1 - x)*(1 - 11*x)^2). - Vincenzo Librandi, Oct 23 2012

Mathematica

CoefficientList[Series[1/((1 - x)(1 - 11*x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 23 2012 *)

Prog

(Magma) I:=[1, 23]; [n le 2 select I[n] else 22*Self(n-1) - 121*Self(n-2) + 1: n in [1..30]]; // Vincenzo Librandi, Oct 23 2012
(PARI) a(n) = (1+11^n*(10*n-1))/100; \\ Jinyuan Wang, Mar 11 2020

Crossrefs

Sequence in context: A264321 A285234 A046493 * A353117 A016267 A142821

Adjacent sequences: A014923 A014924 A014925 * A014927 A014928 A014929

Keyword

nonn,easy

Author

Olivier Gérard

Status

approved