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A000641 Number of paraffins C_n H_{2n-1} X_3 with n carbon atoms.
(Formerly M1456 N0575)
0
0, 1, 2, 5, 14, 39, 109, 312, 890, 2552, 7325, 21047, 60465, 173750, 499068, 1433071, 4113105, 11799780, 33834367, 96968462, 277771344, 795310628, 2276055442, 6510786627, 18616389094, 53207964655, 152014267327, 434136228215 (list; graph; refs; listen; history; internal format)
OFFSET

0,3

REFERENCES

G. Polya, Algebraische Berechnung der Anzahl der Isomeren einiger organischer Verbindungen, Zeit. f. Kristall., 93 (1936), 415-443; line 7 of Table I.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

FORMULA

G.f.: A(x) = ((x*r)/6)*( 1/(1-x*R)^3 + 3/((1-x*R)*(1-x^2*R2)) + 2/(1-x^3*R3)); r = A000598(x), R=A000642(x)/x, Ri=R(x^i).

CROSSREFS

Sequence in context: A142586 A202207 A132834 * A026135 A201778 A105641

Adjacent sequences:  A000638 A000639 A000640 * A000642 A000643 A000644

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified February 16 08:51 EST 2012. Contains 205894 sequences.