OFFSET
0
COMMENTS
Decimal expansion of 9000001/90000000. - Elmo R. Oliveira, May 29 2024
LINKS
FORMULA
a(0)=1; for 0 < n < 7 a(n)=0; for n >= 7, a(n)=1.
This sequence is the inverse Euler transformation of A185327.
G.f.: (x^7-x+1)/(1-x). - Elmo R. Oliveira, May 29 2024
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.
MATHEMATICA
PadRight[{1, 0, 0, 0, 0, 0, 0}, 100, 1] (* Paolo Xausa, Jun 30 2024 *)
CROSSREFS
2-regular simple graphs with girth at least 7: this sequence (connected), A185227 (disconnected), A185327 (not necessarily connected).
Connected k-regular simple graphs with girth at least 7: A186727 (any k), A186717 (triangle); specific k: this sequence (k=2), A014375 (k=3).
Connected 2-regular simple graphs with girth at least g: A179184 (g=3), A185114 (g=4), A185115 (g=5), A185116 (g=6), this sequence (g=7), A185118 (g=8), A185119 (g=9).
KEYWORD
nonn,easy
AUTHOR
Jason Kimberley, Jan 28 2011
STATUS
approved