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A165878
Number of disconnected 8-regular simple graphs on n vertices.
11
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 7, 100, 10901, 3470736, 1473822243, 734843169811, 423929978716908, 281768931380519766, 215039290728074333738, 187766225244288486398132, 186874272297562916477691894, 211165081721567703008217979077
OFFSET
0,21
FORMULA
a = A180260 - A014378 = Euler_transformation(A014378) - A014378.
a(n) = D(n, 8) in the triangle A068933.
EXAMPLE
The a(18)=1 graph is K_9+K_9.
CROSSREFS
8-regular simple graphs: A014378 (connected), this sequence (disconnected), A180260 (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), A165877 (k=7), this sequence (k=8), A185293 (k=9), A185203 (k=10), A185213 (k=11).
Sequence in context: A357336 A182529 A322909 * A175345 A142358 A210684
KEYWORD
nonn,hard
AUTHOR
Jason Kimberley, Sep 29 2009
EXTENSIONS
Terms a(26) and beyond from Andrew Howroyd, May 20 2020
STATUS
approved