60,2

The total number of carbons in 21 free hexagons is 6*21=126, but since they have to be attached (form overlapping molecules sharing edges) the sequence ends already at compounds with 86 carbons. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 02 2008

G. Brinkmann, G. Caporossi and P. Hansen, "A survey and new results on computer enumeration of polyhex and fusene hydrocarbons", J. Chem. Inf. Comput. Sci., vol. 43 (2003) pp. 842-851. See Table 4 column 5 on page 846.

G. Brinkmann, G. Caporossi and P. Hansen, A survey and new results on computer enumeration of polyhex and fusene hdyrocarbons, J Chem. Inf Comput. Sci vol 43 no 3 (2003) pp 842-851.

If n=70 then the number of benzenoids with 21 hexagons with D_(2h) symmetry is 16.

If n=86 then the number of benzenoids with 21 hexagons with D_(2h) symmetry is 40.

Starting value of n is 60 and is even.

For n=10, there are 16 different forms of C_70H_30 of benzenoids of 21 hexagons attached along at least one edge, which each have D_(2h) planar symmetry.

Sequence in context: A100464 A114891 A045716 this_sequence A023660 A161339 A023562

Adjacent sequences: A122536 A122537 A122538 this_sequence A122540 A122541 A122542

nonn,fini,full

Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Sep 18 2006

Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 02 2008