A199318 3*6^n+1.
4, 19, 109, 649, 3889, 23329, 139969, 839809, 5038849, 30233089, 181398529, 1088391169, 6530347009, 39182082049, 235092492289, 1410554953729, 8463329722369, 50779978334209, 304679870005249, 1828079220031489, 10968475320188929
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (7,-6).
Programs
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Magma
[3*6^n+1: n in [0..30]];
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Mathematica
3 6^Range[0,20] +1 (* or *) LinearRecurrence[{7,-6},{4,19},30] (* Harvey P. Dale, Sep 30 2020 *)
Formula
a(n) = 6*a(n-1)-5.
a(n) = 7*a(n-1)-6*a(n-2).
G.f.: (4-9*x)/((1-x)*(1-6*x)).