login
A370847
a(n) = (n-1)*n!*(n-1)!.
0
0, 2, 24, 432, 11520, 432000, 21772800, 1422489600, 117050572800, 11851370496000, 1448500838400000, 210322321735680000, 35793035117199360000, 7057193423941140480000, 1596011435875919462400000, 410402940653807861760000000, 119071573181691454291968000000
OFFSET
1,2
COMMENTS
For n > 2, the number of minimum vertex colorings of the n-barbell graph.
a(n) is also the number of minimum distinguishing labelings of the (n-1) x (n-1) complete bipartite graph K_n,n. - Eric W. Weisstein, Sep 07 2024
LINKS
Eric Weisstein's World of Mathematics, Barbell Graph.
Eric Weisstein's World of Mathematics, Distinguishing Number.
Eric Weisstein's World of Mathematics, Minimum Vertex Coloring.
MATHEMATICA
Table[(n - 1) n! (n - 1)!, {n, 20}]
Table[(n - 1) n Gamma[n]^2, {n, 20}]
Table[2 Binomial[n, 2] Gamma[n]^2, {n, 20}]
CROSSREFS
Sequence in context: A214688 A364195 A003102 * A304318 A337505 A228843
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Mar 03 2024
STATUS
approved