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URL: https://oeis.org/A098610

⇱ A098610 - OEIS

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A098610
a(n) = 10^n + (-1)^n.
3
2, 9, 101, 999, 10001, 99999, 1000001, 9999999, 100000001, 999999999, 10000000001, 99999999999, 1000000000001, 9999999999999, 100000000000001, 999999999999999, 10000000000000001, 99999999999999999, 1000000000000000001, 9999999999999999999, 100000000000000000001
OFFSET
0,1
FORMULA
a(n) = A098611(n) + 2*(-1)^n.
a(n) = A098609(n)/A098611(n).
a(n) = A098609(n)/(11*A015585(n)).
a(n) = 9*A094028(n+1)/A015585(n).
From Chai Wah Wu, Sep 22 2016: (Start)
a(n) = 9*a(n-1) + 10*a(n-2) for n > 1.
G.f.: (9*x - 2)/((x + 1)*(10*x - 1)). (End)
E.g.f.: exp(-x)*(exp(11*x) + 1). - Elmo R. Oliveira, Aug 17 2024
MATHEMATICA
Total/@Partition[Riffle[10^Range[0, 20], {1, -1}], 2] (* or *) Table[10^n+(-1)^n, {n, 0, 20}] (* Harvey P. Dale, Aug 20 2012 *)
PROG
(Magma) [10^n+(-1)^n: n in [0..20]]; // Vincenzo Librandi, Sep 23 2016
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Henry Bottomley, Sep 17 2004
STATUS
approved