A086573 - OEIS

A086573

a(n) = 2*(10^n - 1).

0, 18, 198, 1998, 19998, 199998, 1999998, 19999998, 199999998, 1999999998, 19999999998, 199999999998, 1999999999998, 19999999999998, 199999999999998, 1999999999999998, 19999999999999998, 199999999999999998, 1999999999999999998, 19999999999999999998, 199999999999999999998

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OFFSET

0,2

COMMENTS

Original definition: a(n) = k where R(k+2) = 2.

LINKS

Table of n, a(n) for n=0..20.

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

FORMULA

a(n) = 2*9*A002275(n) = 2*A002283(n).

R(a(n)) = A086580(n).

From Chai Wah Wu, Jul 08 2016: (Start)

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

G.f.: 18*x/((1 - x)*(1 - 10*x)). (End)

E.g.f.: 2*exp(x)*(exp(9*x) - 1). - Elmo R. Oliveira, Sep 12 2024

CROSSREFS

Cf. A002275, A004086 (R(n)), A083812.

One of family of sequences of form a(n) = k, where R(k+m) = m, m=1 to 9; m=1: A002283, m=2: A086573, m=3: A086574, m=4: A086575, m=5: A086576, m=6: A086577, m=7: A086578, m=8: A086579, m=9: A086580.

Sequence in context: A073397 A020920 A083812 * A097515 A177358 A026881

Adjacent sequences: A086570 A086571 A086572 * A086574 A086575 A086576

KEYWORD

nonn,easy

AUTHOR

Ray Chandler, Jul 22 2003

EXTENSIONS

Edited by Jinyuan Wang, Aug 04 2021

STATUS

approved