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A156605 a(n) = (4^n + 20)/3. 2
7, 8, 12, 28, 92, 348, 1372, 5468, 21852, 87388, 349532, 1398108, 5592412, 22369628, 89478492, 357913948, 1431655772, 5726623068, 22906492252, 91625968988, 366503875932, 1466015503708, 5864062014812, 23456248059228, 93824992236892, 375299968947548 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = -A156591(2n+1).

a(n) = 4 + A154879(2n) = 7 + A002450(n).

a(n) = 4*a(n-1) - 20, n > 0.

G.f.: (7 - 27*x)/((1-x)*(1-4*x)). - R. J. Mathar, Feb 23 2009

E.g.f.: (1/3)*(20*exp(x) + exp(4*x)). - G. C. Greubel, Jun 25 2021

MATHEMATICA

(4^Range[0, 40] + 20)/3 (* G. C. Greubel, Jun 25 2021 *)

PROG

(MAGMA) [(4^n+20)/3: n in [0..35]]; // Vincenzo Librandi, Jul 24 2011

(Sage) [(4^n + 20)/3 for n in (0..40)] # G. C. Greubel, Jun 25 2021

CROSSREFS

Cf. A002450, A154879, A156591.

Sequence in context: A105832 A059177 A065729 * A343298 A061905 A308887

Adjacent sequences:  A156602 A156603 A156604 * A156606 A156607 A156608

KEYWORD

nonn,easy

AUTHOR

Paul Curtz, Feb 11 2009

EXTENSIONS

Edited and extended by R. J. Mathar, Feb 23 2009

STATUS

approved

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Last modified June 30 11:45 EDT 2022. Contains 354939 sequences. (Running on oeis4.)