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A002042 a(n) = 7*4^n. 10
7, 28, 112, 448, 1792, 7168, 28672, 114688, 458752, 1835008, 7340032, 29360128, 117440512, 469762048, 1879048192, 7516192768, 30064771072, 120259084288, 481036337152, 1924145348608, 7696581394432, 30786325577728, 123145302310912, 492581209243648 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Subsequence of A000069, the odious numbers. - Reinhard Zumkeller, Aug 26 2007

A rectangular prism with edge lengths 2^n, 2^(n+1) and 2^(n+2) has a surface area 2* (2^n*2^(n+1)+ 2^(n+1)*2^(n+2) + 2^n*2^(n+2)) which equals 4*a(n). - J. M. Bergot, Aug 07 2013

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..500

Tanya Khovanova, Recursive Sequences

Index entries for linear recurrences with constant coefficients, signature (4).

FORMULA

a(n) = 4*a(n-1), n>0; a(0)=7. G.f.: 7/(1-4*x). - Philippe Deléham, Nov 23 2008

a(n) = 7*A000302(n). - Michel Marcus, Jun 24 2015

MATHEMATICA

7*4^Range[0, 100] (* Vladimir Joseph Stephan Orlovsky, Jun 09 2011 *)

CoefficientList[Series[7/(1 - 4 x), {x, 0, 33}], x] (* Vincenzo Librandi, Jun 25 2015 *)

PROG

(MAGMA) [7*4^n: n in [0..30]]; // Vincenzo Librandi, May 31 2011

(PARI) a(n)=7<<(2*n) \\ Charles R Greathouse IV, Apr 17 2012

CROSSREFS

First differences of A083597. Bisection of A005009.

Sequence in context: A243150 A026642 A200467 * A200666 A207098 A037597

Adjacent sequences:  A002039 A002040 A002041 * A002043 A002044 A002045

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified June 27 19:44 EDT 2017. Contains 288790 sequences.