

A124872


Denominator of imaginary part of (2*omega)^(n) where omega = (1 + i*3)/ 2.


4



1, 10, 50, 500, 625, 25000, 125000, 1250000, 390625, 62500000, 312500000, 3125000000, 1953125000, 156250000000, 781250000000, 7812500000000, 1220703125000, 390625000000000, 1953125000000000, 19531250000000000
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OFFSET

0,2


COMMENTS

See A124871 for comments and references.


LINKS

Table of n, a(n) for n=0..19.


FORMULA

a(n) = denominator(Im(1/(1 + i*3)^n). 1/(1 + i*3)^n = A124869(n)/ A124870(n) + i*A124871(n)/A124872(n).


EXAMPLE

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.


CROSSREFS

Cf. A124869A124872.
Sequence in context: A154410 A060156 A000450 * A240534 A223161 A216156
Adjacent sequences: A124869 A124870 A124871 * A124873 A124874 A124875


KEYWORD

easy,frac,nonn


AUTHOR

Jonathan Vos Post, Nov 11 2006


EXTENSIONS

Removed square roots from definition and formula.  R. J. Mathar, May 02 2009


STATUS

approved



