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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 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-François 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.)