

A185334


Number of not necessarily connected 3regular simple graphs on 2n vertices with girth at least 4.


13



1, 0, 0, 1, 2, 6, 23, 112, 801, 7840, 97723, 1436873, 23791155, 432878091, 8544173926, 181519645163, 4127569521160
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OFFSET

0,5


COMMENTS

The null graph on 0 vertices is vacuously 3regular; since it is acyclic, it has infinite girth.


LINKS

Table of n, a(n) for n=0..16.
Jason Kimberley, Not necessarily connected kregular graphs with girth at least 4
Jason Kimberley, Index of sequences counting not necessarily connected kregular simple graphs with girth at least g


FORMULA

Euler transformation of A014371.


CROSSREFS

3regular simple graphs with girth at least 4: A014371 (connected), A185234 (disconnected), this sequence (not necessarily connected).
Not necessarily connected kregular simple graphs with girth at least 4: A185314 (any k), A185304 (triangle); specified degree k: A008484 (k=2), this sequence (k=3), A185344 (k=4), A185354 (k=5), A185364 (k=6).
Not necessarily connected 3regular simple graphs with girth *at least* g: A005638 (g=3), this sequence (g=4), A185335 (g=5), A185336 (g=6).
Not necessarily connected 3regular simple graphs with girth *exactly* g: A185133 (g=3), A185134 (g=4), A185135 (g=5), A185136 (g=6).
Sequence in context: A063255 A117158 A317128 * A290280 A059513 A132647
Adjacent sequences: A185331 A185332 A185333 * A185335 A185336 A185337


KEYWORD

nonn,more,hard


AUTHOR

Jason Kimberley, Feb 15 2011


STATUS

approved



