A146882 a(n) = 5*(4^(n+1) - 1)/3.
5, 25, 105, 425, 1705, 6825, 27305, 109225, 436905, 1747625, 6990505, 27962025, 111848105, 447392425, 1789569705, 7158278825, 28633115305, 114532461225, 458129844905, 1832519379625, 7330077518505, 29320310074025
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (5,-4).
Programs
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Magma
[5*(4^(n+1)-1)/3: n in [0..40]]; // Vincenzo Librandi, Jul 15 2011
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Mathematica
Table[5*(4^(n+1) -1)/3, {n,0,40}] -
PARI
a(n)=20<<(2*n)\/3-2 \\ Charles R Greathouse IV, Jul 15 2011
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SageMath
[(5/3)*(2^(2*n+2)-1) for n in range(41)] # G. C. Greubel, Oct 12 2022
Formula
a(n) = 5*A002450(n+1).
G.f.: 5 / ( (1-x)*(1-4*x) ). - R. J. Mathar, Jun 26 2011
From G. C. Greubel, Oct 12 2022: (Start)
E.g.f.: (5/3)*(4*exp(4*x) - exp(x)). (End)