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A165877
Number of disconnected 7-regular (septic) graphs on 2n vertices.
11
0, 0, 0, 0, 0, 0, 0, 0, 1, 5, 1562, 21617036, 733460349818, 42703733735064572, 4073409466378991404239, 613990076321940092226829047, 141518698937232822678583027258225
OFFSET
0,10
FORMULA
a = A165628 - A014377 = Euler_transformation(A014377) - A014377.
a(n)=D(2n, 7) in the triangle A068933.
CROSSREFS
7-regular simple graphs: A014377 (connected), this sequence(disconnected), A165628 (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), A165656 (k=6), this sequence (k=7), A165878 (k=8), A185293 (k=9), A185203 (k=10), A185213 (k=11).
Sequence in context: A119747 A177906 A127106 * A366830 A123658 A262628
KEYWORD
nonn,hard,more
AUTHOR
Jason Kimberley, Sep 28 2009
EXTENSIONS
a(13)-a(16) from Andrew Howroyd, May 20 2020
STATUS
approved