A308606 Number of (not necessarily maximal) cliques in the n-transposition graph.

2, 4, 16, 97, 721, 6121, 57961, 604801, 6894721, 85276801, 1137628801, 16286054401, 249080832001, 4053790540801, 69960578688001, 1276290183168001, 24542432538624001, 496183962193920001, 10522301185363968001, 233558592784957440001, 5415639870201200640001, 130946084786091294720001

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

Sequence in context: A009838 A088335 A066318 * A066952 A281964 A297009

Adjacent sequences: A308603 A308604 A308605 * A308607 A308608 A308609

Keyword

nonn

Author

Eric W. Weisstein, Jun 10 2019

Extensions

More terms from Robert Israel, Jun 12 2019

Status

approved