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A124869
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Numerator of real part of (2*omega)^(-n) where omega = (-1 + i*3)/ 2.
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4
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1, -1, -2, 13, 7, -79, 11, 307, -527, -481, 779, -3827, -11753, 42641, 4031, -245453, 164833, 897599, -430441, -1044467, 9653287, -14084239, -8545549, 138785587, 32125393, -758178721, 149387939, 2595790093, -5583548873, -1811852719
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OFFSET
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0,3
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LINKS
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Table of n, a(n) for n=0..29.
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FORMULA
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a(n) = numerator( Re(1/(-1 + i*3)^n) ). 1/(-1 + i*3)^n = A124869(n)/ A124870(n) + i*A124871(n)/A124872(n).
G.f.:(10+x)/(10+2*x+x^2) = 1-1/10*x-2/25*x^2+13/500*x^3+7/2500*x^4-79/25000*x^5+... . - Vladeta Jovovic, Oct 08 2007
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EXAMPLE
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a(0) = 1 = numerator of Re((-1+3*i)^0) = 1/1 + 0*i.
a(1) = -1 = numerator of Re(1/(-1+3*i)) = -1/10 - i*3/10.
a(2) = -2 = numerator of Re((-1+3*i)^(-2)) = -2/25 + i*3/50.
a(3) = 13 = numerator of Re((-1+3*i)^(-3)) = 13/500 + i*9/500.
a(4) = 7 = numerator of Re((-1+3*i)^(-4)) = 7/2500 - i*6/625.
a(5) = -79 = numerator of Re((-1+3*i)^(-5)) = -79/25000 + i*3/25000.
a(6) = 11 = numerator of Re((-1+3*i)^(-6)) = 11/31250 + i*117/125000.
a(7) = 307 = numerator of Re((-1+3*i)^(-7)) = 307/1250000 - i*249/1250000.
a(8) = -527 = numerator of Re((-1+3*i)^(-8)) = -527/6250000 - i*21/390625.
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CROSSREFS
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Sequence in context: A128155 A211366 A158088 * A213825 A157480 A213306
Adjacent sequences: A124866 A124867 A124868 * A124870 A124871 A124872
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KEYWORD
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easy,frac,sign,changed
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AUTHOR
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Jonathan Vos Post, Nov 11 2006
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EXTENSIONS
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Removed square roots from definition and formula. - R. J. Mathar, May 02 2009
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STATUS
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approved
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