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A013730 a(n) = 2^(3n+1). 12
2, 16, 128, 1024, 8192, 65536, 524288, 4194304, 33554432, 268435456, 2147483648, 17179869184, 137438953472, 1099511627776, 8796093022208, 70368744177664, 562949953421312, 4503599627370496, 36028797018963968, 288230376151711744 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

1/2 + 1/16 + 1/128 + 1/1024 + ... = 4/7. - Gary W. Adamson, Aug 29 2008

a(n) = A157176(A016921(n)) = A157176(A016933(n)). - Reinhard Zumkeller, Feb 24 2009

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Tanya Khovanova, Recursive Sequences

Index to divisibility sequences

Index entries for linear recurrences with constant coefficients, signature (8).

FORMULA

a(n)=8*a(n-1), n>0 ; a(0)=2 . G.f.: 2/(1-8x). [From Philippe Deléham, Nov 23 2008]

MAPLE

seq(2^(3*n+1), n=0..19); # Nathaniel Johnston, Jun 26 2011

MATHEMATICA

Table[2^n, {n, 1, 100, 3}] (* and *) 2^(3*Range[0, 40] + 1) (* Vladimir Joseph Stephan Orlovsky, Jun 14 2011 *)

PROG

(MAGMA) [2^(3*n+1): n in [0..30]]; // Vincenzo Librandi, May 04 2011

(PARI) a(n)=2<<(3*n) \\ Charles R Greathouse IV, Jun 14 2011

CROSSREFS

Cf. A013731.

Sequence in context: A069868 A208073 A022027 * A270924 A214623 A161737

Adjacent sequences:  A013727 A013728 A013729 * A013731 A013732 A013733

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified October 21 19:21 EDT 2017. Contains 293698 sequences.