|
|
A185115
|
|
Number of connected 2-regular simple graphs on n vertices with girth at least 5.
|
|
14
|
|
|
1, 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, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0
|
|
LINKS
|
|
|
FORMULA
|
a(0)=1; for 0<n<5 a(n)=0; for n>=5 , a(n)=1.
This sequence is the inverse Euler transformation of A185325.
|
|
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 5: this sequence (connected), A185225 (disconnected), A185325 (not necessarily connected).
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|