A175601 a(n) = 7*(10^n - 9).

7, 637, 6937, 69937, 699937, 6999937, 69999937, 699999937, 6999999937, 69999999937, 699999999937, 6999999999937, 69999999999937, 699999999999937, 6999999999999937, 69999999999999937, 699999999999999937, 6999999999999999937, 69999999999999999937, 699999999999999999937

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..100

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

Formula

From Vincenzo Librandi, Aug 23 2014: (Start)

G.f.: 7*x*(1 + 80*x)/((1 - x)*(1 - 10*x)).

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

From Elmo R. Oliveira, Dec 03 2025: (Start)

E.g.f.: 7*(8 - 9*exp(x) + exp(10*x)).

a(n) = 7*A170955(n). (End)

Mathematica

CoefficientList[Series[7 (1 + 80 x)/((1 - x) (1 - 10 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Aug 23 2014 *)
LinearRecurrence[{11, -10}, {7, 637}, 20] (* Harvey P. Dale, Nov 30 2022 *)

Prog

(Magma) [7*(10^n-9): n in [1..20]]; // Vincenzo Librandi, Aug 23 2014

Crossrefs

Cf. A170955.

Sequence in context: A395273 A182346 A333741 * A246113 A277839 A109542

Adjacent sequences: A175598 A175599 A175600 * A175602 A175603 A175604

Keyword

nonn,easy

Author

Vincenzo Librandi

Status

approved