A185315 - OEIS

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A185315

Number of, not necessarily connected, regular simple graphs on n vertices with girth at least 5.

1, 1, 2, 1, 2, 2, 3, 2, 3, 2, 5, 3, 7, 4, 15, 6, 57, 8, 466, 12, 5801, 24, 91091, 3939, 1744378, 4132022, 163639295, 4018022192, 119026596500

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

Table of n, a(n) for n=0..28.

Jason Kimberley, Index of sequences counting not necessarily connected k-regular simple graphs with girth at least g

FORMULA

a(n) = A186725(n) + A185215(n).

CROSSREFS

Not necessarily connected k-regular simple graphs with girth at least 5: this sequence (any k), A185305 (triangle); specified degree k: A185325 (k=2), A185335 (k=3).

Not necessarily connected regular simple graphs with girth at least g: A005176 (g=3), A185314 (g=4), this sequence (g=5), A185316 (g=6), A185317 (g=7), A185318 (g=8), A185319 (g=9).

Sequence in context: A143966 A260617 A178695 * A232548 A029363 A304708

Adjacent sequences: A185312 A185313 A185314 * A185316 A185317 A185318

KEYWORD

nonn,more,hard

AUTHOR

Jason Kimberley, Dec 12 2012

STATUS

approved