|
|
A185116
|
|
Number of connected 2-regular simple graphs on n vertices with girth at least 6.
|
|
14
|
|
|
1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0
|
|
LINKS
|
|
|
FORMULA
|
a(0)=1; for 0<n<6 a(n)=0; for n>=6 , a(n)=1.
This sequence is the inverse Euler transformation of A185326.
|
|
EXAMPLE
|
The null graph is vacuously 2-regular and, being acyclic, has infinite girth.
There are no 2-regular simple graphs with 1 or 2 vertices.
The n-cycle has girth n.
|
|
CROSSREFS
|
2-regular simple graphs with girth at least 6: this sequence (connected), A185226 (disconnected), A185326 (not necessarily connected).
Connected k-regular simple graphs with girth at least 6: A186726 (any k), A186716 (triangle); specified degree k: this sequence (k=2), A014374 (k=3), A058348 (k=4).
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|