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A035328
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n*(2*n-1)*(2*n+1).
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3
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0, 3, 30, 105, 252, 495, 858, 1365, 2040, 2907, 3990, 5313, 6900, 8775, 10962, 13485, 16368, 19635, 23310, 27417, 31980, 37023, 42570, 48645, 55272, 62475, 70278, 78705, 87780, 97527, 107970, 119133, 131040, 143715, 157182, 171465, 186588
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Bisection of A027480. For n>1, gives area of triangle two of whose cevians bound three smaller triangles with areas n-1, n, n+1 contiguously. - Lekraj Beedassy (blekraj(AT)yahoo.com), Dec 21 2006
a(n) = A204558(2*n) / (2*n). [Reinhard Zumkeller, Jan 18 2012]
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REFERENCES
| Neville, Jacobian Elliptic Functions, 2nd ed., p. 38.
Konrad Knopp, Theory and Application of Infinite Series, Dover, p. 269
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Konrad Knopp, Theorie und Anwendung der unendlichen Reihen, Berlin, J. Springer, 1922. (Original german edition of "Theory and Application of Infinite Series")
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FORMULA
| sum(n>=1, 1/a(n))=2*log(2)-1 - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 05 2002
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PROG
| (MAGMA)[n*(2*n-1)*(2*n+1): n in [0..40]]; // Vincenzo Librandi, Jun 07 2011
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CROSSREFS
| Equals 3 * A000447.
Sequence in context: A152767 A195029 A180816 * A100259 A031205 A174774
Adjacent sequences: A035325 A035326 A035327 * A035329 A035330 A035331
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 05 2002
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