%I A018213
%S A018213 1,5,30,110,365,1001,2520,5720,12190,24310,46252,83980,147070,
%T A018213 248710,408760,653752,1021735,1562275,2343770,3453450,5008003,
%U A018213 7153575,10080720,14024400,19284460,26225628,35304920,47071640
%N A018213 Alkane (or paraffin) numbers l(12,n).
%D A018213 S. M. Losanitsch, Die Isomerie-Arten bei den Homologen der Paraffin-Reihe, 
               Chem. Ber. 30 (1897), 1917-1926.
%D A018213 Winston C. Yang (paper in preparation).
%H A018213 N. J. A. Sloane, <a href="classic.html#LOSS">Classic Sequences</a>
%F A018213 l(c, r) = 1/2 binomial(c+r-3, r) + 1/2 d(c, r), where d(c, r) is binomial((c 
               + r - 3)/2, r/2) if c is odd and r is even, 0 if c is even and r 
               is odd, binomial((c + r - 4)/2, r/2) if c is even and r is even, 
               binomial((c + r - 4)/2, (r - 1)/2) if c is odd and r is odd.
%Y A018213 Sequence in context: A071252 A030506 A062990 this_sequence A047661 A000649 
               A027173
%Y A018213 Adjacent sequences: A018210 A018211 A018212 this_sequence A018214 A018215 
               A018216
%K A018213 nonn
%O A018213 0,2
%A A018213 N. J. A. Sloane (njas(AT)research.att.com), Winston C. Yang (yang(AT)math.wisc.edu)