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).
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
Offset: 0
Keywords
Links
- 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