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A070875
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Binary expansion is 1x100...0 where x = 0 or 1.
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5
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5, 7, 10, 14, 20, 28, 40, 56, 80, 112, 160, 224, 320, 448, 640, 896, 1280, 1792, 2560, 3584, 5120, 7168, 10240, 14336, 20480, 28672, 40960, 57344, 81920, 114688, 163840, 229376, 327680, 458752, 655360, 917504, 1310720, 1835008, 2621440
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OFFSET
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0,1
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COMMENTS
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A093873(a(n)) = 2. - Reinhard Zumkeller, Oct 13 2006
For n>1 we have a(n+1) = a(n) + phi(a(n)) where phi is A000010. - Stefan Steinerberger, Dec 20 2007
A 2-automatic sequence. - Charles R Greathouse IV, Sep 24 2012
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LINKS
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Table of n, a(n) for n=0..38.
Index entries for sequences related to linear recurrences with constant coefficients, signature (0,2).
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FORMULA
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Contribution by Bruno Berselli, Mar 01 2011: (Start)
G.f.: (5+7*x)/(1-2*x^2).
a(n) = (6-(-1)^n)*2^((2*n+(-1)^n-1)/4). Therefore: a(n) = 5*2^(n/2) for n even, otherwise a(n) = 7*2^((n-1)/2).
a(n) = 2*a(n-2) for n>1. (End)
a(n+1) = A063757(n) + 6. - Philippe Deléham, Apr 13 2013
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MATHEMATICA
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Flatten@ NestList[ 2# &, {5, 7}, 19] (* Or *)
CoefficientList[ Series[(5 + 7 x)/(1 - 2 x^2), {x, 0, 38}], x] (* Robert G. Wilson v *)
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PROG
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(MAGMA) [n le 2 select 2*n+3 else 2*Self(n-2): n in [1..39]]; // Bruno Berselli, mar 01 2011
(PARI) a(n)=if(n%2, 7, 5)<<(n\2) \\ Charles R Greathouse IV, Sep 24 2012
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CROSSREFS
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Cf. A070876, A123760.
Sequence in context: A020942 A190035 A071911 * A091522 A020711 A183044
Adjacent sequences: A070872 A070873 A070874 * A070876 A070877 A070878
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane, May 19 2002
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EXTENSIONS
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Extended by Robert G. Wilson v, May 20 2002
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STATUS
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approved
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