A255043 a(n) = (5*9^n - 1)/2.

2, 22, 202, 1822, 16402, 147622, 1328602, 11957422, 107616802, 968551222, 8716961002, 78452649022, 706073841202, 6354664570822, 57191981137402, 514727830236622, 4632550472129602, 41692954249166422, 375236588242497802, 3377129294182480222

Offset

0,1

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

Formula

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

Recurrence: a(n) = 10*a(n-1) - 9*a(n-2), n>=2, a(0) = 2, a(1) = 22.

a(n) = 2*A138894(n).

E.g.f.: (5*exp(9*x) - exp(x))/2. - G. C. Greubel, Feb 07 2021

Mathematica

Table[(5*9^n - 1)/2, {n, 0, 19}]
LinearRecurrence[{10, -9}, {2, 22}, 20] (* Harvey P. Dale, Jun 15 2018 *)

Prog

(SageMath) [(5*9^n -1)/2 for n in (0..20)] # G. C. Greubel, Feb 07 2021
(Magma) [(5*9^n -1)/2: n in [0..20]]; // G. C. Greubel, Feb 07 2021

Crossrefs

Cf. A096053, A138894, A191681, A198964, A198969.

Row 2 of A255044.

Sequence in context: A279801 A043037 A058441 * A359856 A366919 A308313

Adjacent sequences: A255040 A255041 A255042 * A255044 A255045 A255046

Keyword

nonn,easy

Author

L. Edson Jeffery, Feb 13 2015

Status

approved