A185044 Number of disconnected 4-regular simple graphs on n vertices with girth exactly 4.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 2, 15, 35, 247, 1692, 17409, 197924, 2492824, 33117880, 461597957, 6709514218, 101153412903, 1597440868898

Offset

0,19

Comments

Only one component need have girth exactly four; the other components need only have girth at least four.

First differs from A185244 at n = 38, the smallest n where A185245 is nonzero.

Links

Table of n, a(n) for n=0..31.

Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth exactly g

Formula

a(n) = A185244(n) - A185245(n).

a(n) = A185144(n) - A184944(n).

Crossrefs

Disconnected 4-regular simple graphs with girth exactly g: A185043 (g=3), this sequence (g=4).

Disconnected k-regular simple graphs with girth exactly 4: A185034 (k=3), this sequence (k=4).

Sequence in context: A009773 A325912 A365086 * A185244 A329920 A006929

Adjacent sequences: A185041 A185042 A185043 * A185045 A185046 A185047

Keyword

nonn,hard,more

Author

Jason Kimberley, Nov 04 2011

Extensions

a(31) corrected by the author, propagated from A185244, Jan 05 2013

Status

approved