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A210714 Number of disconnected regular simple graphs on n vertices with girth exactly 4. 1
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 3, 2, 5, 3, 15, 5, 44, 10, 203, 47, 1415, 1710, 27771, 197951, 2613710, 33117920, 463707092, 6709514282, 102306345333, 1597440872721 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,13

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) = A185214(n) - A185215(n).

MATHEMATICA

A[s_Integer] := With[{s6 = StringPadLeft[ToString[s], 6, "0"]}, Cases[ Import["https://oeis.org/A" <> s6 <> "/b" <> s6 <> ".txt", "Table"], {_, _}][[All, 2]]];

A185214 = A@185214;

A185215 = A@185215;

a[n_] := A185214[[n + 1]] - A185215[[n + 1]];

a /@ Range[0, 31] (* Jean-Fran├žois Alcover, Jan 27 2020 *)

CROSSREFS

Sequence in context: A331847 A130912 A178844 * A143956 A110661 A143124

Adjacent sequences:  A210711 A210712 A210713 * A210715 A210716 A210717

KEYWORD

nonn,more,hard

AUTHOR

Jason Kimberley, Dec 10 2012

EXTENSIONS

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

STATUS

approved

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Last modified February 20 16:30 EST 2020. Contains 332078 sequences. (Running on oeis4.)