OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..447
Eric Weisstein's World of Mathematics, Clique
Eric Weisstein's World of Mathematics, Transposition Graph
FORMULA
a(n) = 1 + (n^2 - n + 4)*n!/4. - Robert Israel, Jun 12 2019
MAPLE
seq(1 + (n^2 - n + 4)*n!/4, n=1..30); # Robert Israel, Jun 12 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Jun 10 2019
EXTENSIONS
More terms from Robert Israel, Jun 12 2019
STATUS
approved