OFFSET
1,2
COMMENTS
Cycles have length at least 2, and may repeat vertices but not edges.
Cycles p,q are equivalent if the vertex-edge sequence of q can be made by rotating or reversing that of p.
LINKS
Simon R. Donnelly, Table of n, a(n) for n = 1..60
Simon R. Donnelly, Python program
Eric W. Weisstein, Multigraph
EXAMPLE
For n=2 the a(n) = 33 unique cycles' vertex-edge sequences are:
a0b1a, b2c3b, c4a5c;
a0b2c4a, a0b2c5a, a0b3c4a, a0b3c5a, a1b2c4a, a1b2c5a, a1b3c4a, a1b3c5a;
a0b2c3b1a, a0b3c2b1a, b2c4a5c3b, b2c5a4c3b, c4a0b1a5c, c4a1b0a5c;
a0b2c4a1b3c5a, a1b2c4a0b3c5a, a0b3c4a1b2c5a, a0b2c5a1b3c4a;
a0b2c4a5c3b1a, a1b2c4a5c3b0a, a0b3c4a5c2b1a, a0b2c5a4c3b1a;
b2c4a0b1a5c3b, b3c4a0b1a5c2b, b2c5a0b1a4c3b, b2c4a1b0a5c3b;
c4a0b3c4b1a5c, c5a0b3c4b1a4c, c4a1b3c4b0a5c, c4a0b4c3b1a5c.
PROG
(Python) See links.
CROSSREFS
KEYWORD
nonn,walk
AUTHOR
Simon R. Donnelly, Oct 09 2015
STATUS
approved