OFFSET
1,2
LINKS
Eric Weisstein's World of Mathematics, Rook Graph
Eric Weisstein's World of Mathematics, Spanning Tree
FORMULA
a(n) = n^(2*n-4) * (2*n)^((n-1)^2). - Sean A. Irvine, Oct 26 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Jul 16 2011
EXTENSIONS
Initial term a(1)=1 added by N. J. A. Sloane, Jun 21 2017
STATUS
approved