OFFSET
0,2
COMMENTS
A258017(n) gives the count of terms with binary width 2n + 1.
Differs from A258003 for the first time at n=875, which here contains a(875) = 131821024 the smallest polyhex (26 edges, six hexes) where two hexes (at the opposite ends of a coiled pattern) meet to touch each other.
This pattern is isomorphic to benzenoid [6]Helicene (up to chirality, see the illustrations at Wikipedia-page).
Note that here, in contrast to "Boundary Edges Code for Benzenoid Systems" (see links at A258012), if a fusene has no bilateral symmetry then both variants of the corresponding one-sided fusene (their codes) are included in this sequence, the other obtained from the other by turning it over.
LINKS
Antti Karttunen, Table of n, a(n) for n = 0..875
Eric Weisstein's World of Mathematics, Fusene
Wikipedia, Helicene
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, May 31 2015
STATUS
approved