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A165656
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Number of disconnected 6-regular (sextic) graphs on n vertices.
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12
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 5, 25, 297, 8199, 377004, 22014143, 1493574756, 114880777582, 9919463450855, 955388277929620, 102101882472479938, 12050526046888229845, 1563967741064673811531, 222318116370232302781485, 34486536277291555593662301, 5817920265098158804699762770
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OFFSET
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0,17
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LINKS
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Table of n, a(n) for n=0..31.
N. J. A. Sloane, Transforms
Jason Kimberley, Disconnected regular graphs (with girth at least 3)
Jason Kimberley, Index of sequences counting disconnected k-regular simple graphs with girth at least g
Eric Weisstein's World of Mathematics, Disconnected Graph
Eric Weisstein's World of Mathematics, Regular Graph
Eric Weisstein's World of Mathematics, Sextic Graph
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FORMULA
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a = A165627 - A006822 = Euler_transformation(A006822) - A006822.
a(n) = D(n, 6) in the triangle A068933.
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CROSSREFS
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6-regular simple graphs: A006822 (connected), this sequence (disconnected), A165627 (not necessarily connected).
Disconnected regular simple graphs: A068932 (any degree), A068933 (triangular array), specified degree k: A165652 (k=2), A165653 (k=3), A033483 (k=4), A165655 (k=5), this sequence (k=6), A165877 (k=7), A165878 (k=8), A185293 (k=9), A185203 (k=10), A185213 (k=11).
Sequence in context: A184958 A145076 A185063 * A145773 A197195 A285602
Adjacent sequences: A165653 A165654 A165655 * A165657 A165658 A165659
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KEYWORD
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nonn,hard
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AUTHOR
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Jason Kimberley, Sep 28 2009
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EXTENSIONS
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Terms a(25) and beyond from Andrew Howroyd, May 20 2020
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STATUS
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approved
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