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A163834
a(n) = (4^n + 5)/3.
7
2, 3, 7, 23, 87, 343, 1367, 5463, 21847, 87383, 349527, 1398103, 5592407, 22369623, 89478487, 357913943, 1431655767, 5726623063, 22906492247, 91625968983, 366503875927, 1466015503703, 5864062014807, 23456248059223, 93824992236887, 375299968947543
OFFSET
0,1
FORMULA
a(n) = (4^n + 5)/3 = A135351(2*n+1) = A140966(2*n) = A153643(2*n).
a(n) = 5*a(n-1) - 4*a(n-2).
G.f.: (2-7*x)/((4*x-1)*(x-1)).
a(n+1) - a(n) = A000302(n).
E.g.f.: (1/3)*(5*exp(x) + exp(4*x)). - G. C. Greubel, Aug 05 2017
MATHEMATICA
Table[(4^n + 5)/3, {n, 0, 50}] (* G. C. Greubel, Aug 05 2017 *)
LinearRecurrence[{5, -4}, {2, 3}, 30] (* Harvey P. Dale, Jun 14 2023 *)
PROG
(PARI) x='x+O('x^50); concat([0], Vec((2-7*x)/((4*x-1)*(x-1)))) \\ G. C. Greubel, Aug 05 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Offset set to 0 by R. J. Mathar, Aug 06 2009
STATUS
approved

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