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A005997
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Number of paraffins.
(Formerly M2832)
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5
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1, 3, 10, 20, 39, 63, 100, 144, 205, 275, 366, 468, 595, 735, 904, 1088, 1305, 1539, 1810, 2100, 2431, 2783, 3180, 3600, 4069, 4563, 5110, 5684, 6315, 6975, 7696, 8448, 9265, 10115, 11034, 11988, 13015
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| S. M. Losanitsch, Die Isomerie-Arten bei den Homologen der Paraffin-Reihe, Chem. Ber. 30 (1897), 1917-1926.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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FORMULA
| G.f.: (x^3+3*x^2+x+1)*x / ((-1+x)^2*(-1+x^2)^2).
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MAPLE
| a:= n-> (Matrix([[0, 0, -1, -5, -12, -26]]). Matrix(6, (i, j)-> if (i=j-1) then 1 elif j=1 then [2, 1, -4, 1, 2, -1][i] else 0 fi)^n)[1, 1]; seq (a(n), n=1..37); # Alois P. Heinz, Jul 31 2008
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CROSSREFS
| Sequence in context: A098645 A089693 A194116 * A081205 A092305 A196166
Adjacent sequences: A005994 A005995 A005996 * A005998 A005999 A006000
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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