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A111918
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Numerator of x(n) = Sum((odd part of k)/(k^3): 1<=k<=n).
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5
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1, 9, 89, 721, 18601, 2089, 103961, 832913, 68093153, 68347169, 8320810649, 8331482849, 1414167788681, 1416817979081, 1421435199689, 11373510649537, 3295255574810593, 366551352989977, 132591913780524097, 132652127531625601
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Denominator of x(n) = A111919(n);
x(n) = a(n)/A111919(n) ---> Pi*Pi/7 = 6*zeta(2)/7.
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REFERENCES
| G. Polya and G. Szego, Problems and Theorems in Analysis II (Springer 1924, reprinted 1972), Part Eight, Chap. 1, Sect. 6, Problem 50.
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LINKS
| Eric Weisstein's World of Mathematics, Odd Part
Eric Weisstein's World of Mathematics, Rieman n Zeta Function zeta(2)
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EXAMPLE
| a(50) = 429245027972423430658635002176171233144054521,
A111919(50) = 307330458857514095936081844184308729630720000:
x(50)=a(50)/A111919(50)=1.39668..., x(50)*7/6=1.62946....
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CROSSREFS
| Cf. A000265, A013661, A111929, A111920, A111922.
Sequence in context: A178369 A055410 A175371 * A064616 A133486 A198967
Adjacent sequences: A111915 A111916 A111917 * A111919 A111920 A111921
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KEYWORD
| nonn,frac
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 21 2005
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