OFFSET
0,5
COMMENTS
Also counts number of n-cycloalkanes and single bonded allotropes with n carbon atoms.
Stereoisomerism is not taken into account. Some of the drawn structures may or may not exist due to their strained geometries.
EXAMPLE
a(4) = 3, because here are 3 molecules with 4 carbons following the above rule: cyclobutane, bicyclobutane, tetrahedrane.
a(5) = 11, because there are 11 molecules with 5 carbons following above rule: cyclopentane, housane, spiropentane, pyramidane, bicyclopentane, propellane, tricyclo[2.1.0.0^(1,3)]pentane, tricyclo[2.1.0.0^(2,5)]pentane tetracyclopentane, pentacyclopentane, hexacyclopentane.
PROG
(nauty/bash) geng -c -D4 -d2 ${n} -q | multig -m1 -D4 -u
CROSSREFS
KEYWORD
nonn
AUTHOR
Natan Arie Consigli, Aug 03 2017
EXTENSIONS
a(15)-a(24) from Andrew Howroyd, Mar 20 2020
STATUS
approved