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A013731 2^(3n+2). 7
4, 32, 256, 2048, 16384, 131072, 1048576, 8388608, 67108864, 536870912, 4294967296, 34359738368, 274877906944, 2199023255552, 17592186044416, 140737488355328, 1125899906842624, 9007199254740992, 72057594037927936, 576460752303423488 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Starting rank of the (j-1)-Washtenaw series for the fixed ratio 2^(-j-1) (see Griess). - J. Taylor (jt_cpp(AT)yahoo.com), Apr 03 2004

1/4 + 1/32 + 1/256 + 1/2048 + ... = 2/7 - Gary W. Adamson, Aug 29 2008

LINKS

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

Tanya Khovanova, Recursive Sequences

Robert L. Griess Jr. Pieces of 2^d: Existence and uniqueness for Barnes-Wall and Ypsilanti lattices. Mar 28 2004. See Definition 14.21.

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)=4 . G.f.: 4/(1-8x). - Philippe Deléham, Nov 23 2008

a(n) = A198852(n) + 1. - Michel Marcus, Aug 23 2013

MAPLE

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

PROG

(Sage) [lucas_number1(3*n, 2, 0) for n in xrange(1, 20)] # - Zerinvary Lajos, Oct 27 2009

(MAGMA) [2^(3*n+2): n in [0..20]]; // Vincenzo Librandi, Jun 26 2011

(PARI) a(n)=4<<(3*n) \\ Charles R Greathouse IV, Apr 07 2012

CROSSREFS

Cf. A013730.

Sequence in context: A108449 A213413 A092811 * A009509 A036725 A065089

Adjacent sequences:  A013728 A013729 A013730 * A013732 A013733 A013734

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Replaced arXiv URL by non-cached version - R. J. Mathar, Oct 23 2009

STATUS

approved

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Last modified March 23 20:33 EDT 2017. Contains 283965 sequences.