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Search: id:A124872
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| A124872 |
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Denominator of imaginary part of (2*omega)^(-n) where omega = (-1 + i*3)/ 2. |
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+0
4
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| 1, 10, 50, 500, 625, 25000, 125000, 1250000, 390625, 62500000, 312500000, 3125000000, 1953125000, 156250000000, 781250000000, 7812500000000, 1220703125000, 390625000000000, 1953125000000000, 19531250000000000
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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See A124871 for comments and references.
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FORMULA
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a(n) = denominator(Im(1/(-1 + i*3)^n). 1/(-1 + i*3)^n = A124869(n)/ A124870(n) + i*A124871(n)/A124872(n).
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EXAMPLE
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a(0) = 1 = denominator of Im((-1+3*i)^0) = 1/1 + 0*i.
a(1) = 10 = denominator of Im(1/(-1+3*i)) = -1/10 - i*3/10.
a(2) = 50 = denominator of Im((-1+3*i)^(-2)) = -2/25 + i*3/50.
a(3) = 500 = denominator of Im((-1+3*i)^(-3)) = 13/500 + i*9/500.
a(4) = 625 = denominator of Im((-1+3*i)^(-4)) = 7/2500 - i*6/625.
a(5) = 25000 = denominator of Im((-1+3*i)^(-5)) = -79/25000 + i*3/25000.
a(6) = 125000 = denominator of Im((-1+3*i)^(-6)) = 11/31250 + i*117/125000.
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CROSSREFS
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Cf. A124869-A124872.
Sequence in context: A154410 A060156 A000450 this_sequence A072296 A143558 A106041
Adjacent sequences: A124869 A124870 A124871 this_sequence A124873 A124874 A124875
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KEYWORD
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easy,frac,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 11 2006
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EXTENSIONS
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Removed square roots from definition and formula. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 02 2009
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