A199680 a(n) = (11*9^n+1)/2.

6, 50, 446, 4010, 36086, 324770, 2922926, 26306330, 236756966, 2130812690, 19177314206, 172595827850, 1553362450646, 13980262055810, 125822358502286, 1132401226520570, 10191611038685126, 91724499348166130, 825520494133495166

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (10,-9).

Formula

a(n) = 9*a(n-1)-4.

a(n) = 10*a(n-1)-9*a(n-2).

G.f.: 2*(3-5*x)/((1-x)*(1-9*x)).

Mathematica

(11*9^Range[0, 20] + 1)/2 (* Wesley Ivan Hurt, Apr 26 2023 *)
LinearRecurrence[{10, -9}, {6, 50}, 20] (* Harvey P. Dale, Oct 23 2024 *)

Prog

(Magma) [(11*9^n+1)/2: n in [0..30]];

Crossrefs

Sequence in context: A090409 A212233 A180910 * A039742 A243667 A365189

Adjacent sequences: A199677 A199678 A199679 * A199681 A199682 A199683

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 09 2011

Status

approved