A086949 Numbers k such that R(k+9) = 5.
41, 491, 4991, 49991, 499991, 4999991, 49999991, 499999991, 4999999991, 49999999991, 499999999991, 4999999999991, 49999999999991, 499999999999991, 4999999999999991, 49999999999999991, 499999999999999991, 4999999999999999991, 49999999999999999991, 499999999999999999991
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..300
- Index entries for linear recurrences with constant coefficients, signature (11,-10).
Programs
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Magma
[5*10^n-9: n in [1..25] ]; // Vincenzo Librandi, Aug 22 2011
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Mathematica
5*10^Range[20]-9 (* Harvey P. Dale, Nov 29 2018 *)
Formula
a(n) = 5*10^n - 9.
R(a(n)) = A086946(n).
From Stefano Spezia, Dec 15 2022: (Start)
O.g.f.: x*(41 + 40*x)/((1 - x)*(1 - 10*x)).
E.g.f.: 4 - 9*exp(x) + 5*exp(10*x).
a(n) = 11*a(n-1) - 10*a(n-2) for n > 2. (End)