A199686 a(n) = 6*10^n + 1.
7, 61, 601, 6001, 60001, 600001, 6000001, 60000001, 600000001, 6000000001, 60000000001, 600000000001, 6000000000001, 60000000000001, 600000000000001, 6000000000000001, 60000000000000001, 600000000000000001, 6000000000000000001, 60000000000000000001, 600000000000000000001
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (11,-10).
Programs
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Magma
[6*10^n+1: n in [0..30]];
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Mathematica
6*10^Range[0,20]+1 (* or *) LinearRecurrence[{11,-10},{7,61},20] (* Harvey P. Dale, Oct 23 2024 *)
Formula
a(n) = 10*a(n-1) - 9.
a(n) = 11*a(n-1) - 10*a(n-2).
G.f.: (7-16*x)/((1-x)*(1-10*x)).
E.g.f.: exp(x)*(1 + 6*exp(9*x)). - Elmo R. Oliveira, Jun 10 2025