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A033483
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Number of disconnected 4-valent (or quartic) graphs with n nodes.
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17
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 3, 8, 25, 88, 378, 2026, 13351, 104595, 930586, 9124662, 96699987, 1095469608, 13175272208, 167460699184, 2241578965849, 31510542635443, 464047929509794, 7143991172244290, 114749135506381940, 1919658575933845129, 33393712487076999918, 603152722419661386031
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OFFSET
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0,13
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REFERENCES
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R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
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LINKS
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FORMULA
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MATHEMATICA
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A006820 = Cases[Import["https://oeis.org/A006820/b006820.txt", "Table"], {_, _}][[All, 2]];
(* EulerTransform is defined in A005195 *)
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CROSSREFS
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Disconnected regular simple graphs: A068932 (any degree), A068933 (triangular array), specified degree k: A165652 (k=2), A165653 (k=3), this sequence (k=4), A165655 (k=5), A165656 (k=6), A165877 (k=7), A165878 (k=8), A185293 (k=9), A185203 (k=10), A185213 (k=11).
Disconnected 4-regular simple graphs with girth at least g: this sequence (g=3), A185244 (g=4), A185245 (g=5), A185246 (g=6).
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KEYWORD
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nonn,nice,hard
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AUTHOR
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Ronald C. Read
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EXTENSIONS
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STATUS
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approved
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