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Search: id:A128501
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| A128501 |
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Denominators of partial sums for a series for Pi/(3*sqrt(3)). |
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+0
2
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| 1, 2, 2, 4, 20, 20, 140, 280, 280, 280, 3080, 3080, 40040, 40040, 40040, 80080, 1361360, 1361360, 25865840, 25865840, 25865840, 25865840, 594914320, 594914320, 2974571600, 2974571600, 2974571600, 2974571600, 86262576400
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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The numerators are given in A128500.
See the W. Lang link under A128500.
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FORMULA
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a(n)=denominator(r(n)) with the rationals r(n):=sum(((-1)^k)*S(k,1)/(k+1),k=0..n) with Chebyshev's S-Polynomials S(n,1)=[1,1,0,-1,-1,0] periodic sequence with period 6. See A010892.
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CROSSREFS
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Sequence in context: A006853 A120417 A062267 this_sequence A009541 A006829 A098335
Adjacent sequences: A128498 A128499 A128500 this_sequence A128502 A128503 A128504
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KEYWORD
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nonn,frac,easy
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AUTHOR
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Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de) Apr 04 2007
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