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A086573
a(n) = 2*(10^n - 1).
8
0, 18, 198, 1998, 19998, 199998, 1999998, 19999998, 199999998, 1999999998, 19999999998, 199999999998, 1999999999998, 19999999999998, 199999999999998, 1999999999999998, 19999999999999998, 199999999999999998, 1999999999999999998, 19999999999999999998, 199999999999999999998
OFFSET
0,2
COMMENTS
Original definition: a(n) = k where R(k+2) = 2.
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
KEYWORD
nonn,easy
AUTHOR
Ray Chandler, Jul 22 2003
EXTENSIONS
Edited by Jinyuan Wang, Aug 04 2021
STATUS
approved