A155588 a(n) = 5^n + 2^n - 1^n.
1, 6, 28, 132, 640, 3156, 15688, 78252, 390880, 1953636, 9766648, 48830172, 244144720, 1220711316, 6103532008, 30517610892, 152587956160, 762939584196, 3814697527768, 19073486852412, 95367432689200, 476837160300276
Offset: 0
Links
- Michael De Vlieger, Table of n, a(n) for n = 0..1430
- Index entries for linear recurrences with constant coefficients, signature (8,-17,10).
Programs
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Mathematica
CoefficientList[Series[1/(1 - 5 x) + 1/(1 - 2 x) - 1/(1 - x), {x, 0, 21}], x] (* Michael De Vlieger, Mar 02 2022 *) -
PARI
a(n)=5^n+2^n-1 \\ Charles R Greathouse IV, Sep 24 2015
Formula
G.f.: 1/(1-5*x)+1/(1-2*x)-1/(1-x).
E.g.f.: e^(5*x)+e^(2*x)-e^x.
a(n) = 7*a(n-1)-10*a(n-2)-4 with a(0)=1, a(1)=6. - Vincenzo Librandi, Jul 21 2010
a(n) = A074600(n)-1. - R. J. Mathar, Mar 10 2022