A173810 - OEIS

A173810

a(n) = (8*10^n - 71)/9 for n > 0.

1, 81, 881, 8881, 88881, 888881, 8888881, 88888881, 888888881, 8888888881, 88888888881, 888888888881, 8888888888881, 88888888888881, 888888888888881, 8888888888888881, 88888888888888881, 888888888888888881, 8888888888888888881, 88888888888888888881, 888888888888888888881

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OFFSET

1,2

LINKS

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

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

FORMULA

a(n) = 10*a(n-1) + 71 for n > 0, a(0) = -7.

From Vincenzo Librandi, Jul 05 2012: (Start)

G.f.: x*(1+70*x)/((1-x)*(1-10*x)).

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

E.g.f.: exp(x)*(8*exp(9*x) - 71)/9. - Elmo R. Oliveira, Sep 09 2024