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A022014 Tri-substituted alkanes of form C_n H_{2n-1} X_2 Y, or equivalently bi-substituted alkyls of form -C_n H_{2n-1} X_2 (n=1: CHXXY; n=2: CXXY-CHHH CXYH-CXHH CXXH-CYHH). 1
0, 1, 3, 9, 27, 81, 240, 711, 2094, 6152, 18012, 52613, 153297, 445772, 1293780, 3748820, 10845935, 31336532, 90426198, 260644262, 750502831, 2158961013, 6205225334, 17820505454, 51139664497, 146654181925, 420291420558 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..26.

Sean A. Irvine, Java program (github)

G. Polya, Algebraische Berechnung der Anzahl der Isomeren einiger organischer Verbindungen, Zeit. f. Kristall., 93 (1936), 415-443; line 6 of Table I.

G. Polya, Algebraische Berechnung der Anzahl der Isomeren einiger organischer Verbindungen,  Zeit. f. Kristall., 93 (1936), 415-443; Table I, line 6. (Annotated scanned copy)

FORMULA

G.f.: (1/2) * (x*r(x)/(1-x*R(x)) * (1/(1-x*R(x))^2 + 1/(1-x^2*R(x^2))) where r(x) is the g.f. for A000598 and R(x) is the g.f. for A000642 [from Polya, p. 440]. - Sean A. Irvine, May 13 2019

CROSSREFS

Cf. A000598, A000641, A000642.

Sequence in context: A014953 A274627 A080557 * A181140 A291007 A038002

Adjacent sequences:  A022011 A022012 A022013 * A022015 A022016 A022017

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Paul Zimmermann

STATUS

approved

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Last modified November 22 00:32 EST 2019. Contains 329383 sequences. (Running on oeis4.)