A198694 a(n) = 7*4^n-1.
6, 27, 111, 447, 1791, 7167, 28671, 114687, 458751, 1835007, 7340031, 29360127, 117440511, 469762047, 1879048191, 7516192767, 30064771071, 120259084287, 481036337151, 1924145348607, 7696581394431, 30786325577727, 123145302310911, 492581209243647, 1970324836974591
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
[7*4^n-1: n in [0..30]]
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Mathematica
7*4^Range[0,30]-1 (* or *) LinearRecurrence[{5,-4},{6,27},30] (* Harvey P. Dale, Nov 14 2018 *)
Formula
a(n) = 4*a(n-1)+3.
a(n) = 5*a(n-1)-4*a(n-2), n>1.
G.f.: ( 6-3*x ) / ( (4*x-1)*(x-1) ). - R. J. Mathar, Oct 30 2011
E.g.f.: exp(x)*(7*exp(3*x) - 1). - Stefano Spezia, Apr 17 2024