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Search: id:A005996
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| A005996 |
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Number of paraffins.
(Formerly M1609)
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+0
2
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| 2, 6, 16, 30, 54, 84, 128, 180, 250, 330, 432, 546, 686, 840, 1024, 1224, 1458, 1710, 2000, 2310, 2662, 3036, 3456, 3900, 4394, 4914, 5488, 6090, 6750, 7440, 8192, 8976, 9826, 10710, 11664, 12654, 13718
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
S. M. Losanitsch, Die Isomerie-Arten bei den Homologen der Paraffin-Reihe, Chem. Ber. 30 (1897), 1917-1926.
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FORMULA
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G.f.: 2*(x^2+x+1)/(-1+x)^2/(-1+x^2)^2.
a(n) = 2*(A006918(n) + A006918(n-1) + A006918(n-2)), n>1. - Ralf Stephan, Apr 26 2003
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CROSSREFS
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Sequence in context: A082374 A085226 A071522 this_sequence A032091 A060354 A140131
Adjacent sequences: A005993 A005994 A005995 this_sequence A005997 A005998 A005999
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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