A198974 2*11^n-1.

1, 21, 241, 2661, 29281, 322101, 3543121, 38974341, 428717761, 4715895381, 51874849201, 570623341221, 6276856753441, 69045424287861, 759499667166481, 8354496338831301, 91899459727144321, 1010894056998587541, 11119834626984462961

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..900

Index entries for linear recurrences with constant coefficients, signature (12,-11).

Formula

a(n) = 11*a(n-1)+10.

a(n) = 12*a(n-1)-11*a(n-2), n>1.

G.f.: (1 + 9*x)/(1 - 12*x + 11*x^2). - Vincenzo Librandi, Jan 04 2013

Mathematica

CoefficientList[Series[(1 + 9*x)/(1 - 12*x + 11*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)
2*11^Range[0, 20]-1 (* or *) LinearRecurrence[{12, -11}, {1, 21}, 20] (* Harvey P. Dale, Dec 25 2019 *)

Prog

(Magma) [2*11^n-1 : n in [0..20]]

Crossrefs

Sequence in context: A317428 A089937 A175843 * A271792 A177730 A199300

Adjacent sequences: A198971 A198972 A198973 * A198975 A198976 A198977

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 02 2011

Status

approved