A172525 a(n) = 111111111 * n.
111111111, 222222222, 333333333, 444444444, 555555555, 666666666, 777777777, 888888888, 999999999, 1111111110, 1222222221, 1333333332, 1444444443, 1555555554, 1666666665, 1777777776, 1888888887, 1999999998, 2111111109, 2222222220, 2333333331, 2444444442, 2555555553
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
- Index entries for linear recurrences with constant coefficients, signature (2,-1).
Programs
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Magma
[9*n*12345679: n in [1..20]]; // Vincenzo Librandi, Aug 20 2014
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Mathematica
Table[9 n 12345679, {n, 1, 20}] (* Vincenzo Librandi, Aug 20 2014 *) LinearRecurrence[{2,-1},{111111111,222222222},20] (* Harvey P. Dale, Sep 10 2023 *) -
PARI
Vec(111111111*x/(x-1)^2 + O(x^100)) \\ Colin Barker, Aug 20 2014
Formula
From Colin Barker, Aug 20 2014: (Start)
a(n) = 2*a(n-1) - a(n-2).
G.f.: 111111111*x/(x-1)^2. (End)
From Elmo R. Oliveira, Jun 25 2025: (Start)
E.g.f.: 111111111*x*exp(x).
a(n) = 12345679*A008591(n). (End)