A198857 a(n) = 10*8^n - 1.

9, 79, 639, 5119, 40959, 327679, 2621439, 20971519, 167772159, 1342177279, 10737418239, 85899345919, 687194767359, 5497558138879, 43980465111039, 351843720888319, 2814749767106559, 22517998136852479, 180143985094819839

Offset

0,1

Comments

The subsequence of primes begins: 79, 5119, 1784059615882449851322857461811868920478433279, no more through a(50). - Jonathan Vos Post, Oct 31 2011

Links

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

Index entries for linear recurrences with constant coefficients, signature (9,-8).

Formula

a(n) = 8*a(n-1) + 7.

a(n) = 9*a(n-1) - 8*a(n-2), n>1.

G.f.: (9-2*x)/((8*x-1)*(x-1)). - R. J. Mathar, Oct 31 2011

E.g.f.: exp(x)*(10*exp(7*x) - 1). - Elmo R. Oliveira, Aug 10 2024

Prog

(Magma) [10*8^n-1: n in [0..30]];
(PARI) Vec((9-2*x)/((8*x-1)*(x-1)) + O(x^30)) \\ Michel Marcus, Feb 26 2015

Crossrefs

Sequence in context: A357281 A172203 A293721 * A126632 A294344 A125909

Adjacent sequences: A198854 A198855 A198856 * A198858 A198859 A198860

Keyword

nonn,easy

Author

Vincenzo Librandi, Oct 31 2011

Status

approved