A296785 Detour index for the n-transposition graph.

0, 1, 69, 6216, 846120, 185976720, 63980285040, 32772128296320, 23892198317930880, 23892346459702828800, 31800733054746203116800, 54951669873436196523801600, 120728819293576143371142220800, 331279880265073822312384445491200

Offset

1,3

Comments

Also, the maximum detour index of any bipartite graph on n! nodes. - Andrew Howroyd, Dec 21 2017

Links

Andrew Howroyd, Table of n, a(n) for n = 1..100

Eric Weisstein's World of Mathematics, Transposition Graph

Eric Weisstein's World of Mathematics, Detour Index

Formula

a(n) = n!*(n!/2-1)^2 + (n!/2)^2*(n!-1) for n > 1. - Andrew Howroyd, Dec 20 2017

a(n) = A296819(n!). - Andrew Howroyd, Dec 23 2017

Mathematica

Table[If[n == 1, 0, n! (n! (2 n! - 5) + 4)/4], {n, 20}]

Prog

(PARI) a(n) = if(n==1, 0, n!*(n!/2-1)^2 + (n!/2)^2*(n!-1)) \\ Andrew Howroyd, Dec 20 2017

Crossrefs

Cf. A296782, A296819.

Sequence in context: A207985 A207197 A207217 * A363927 A364024 A264171

Adjacent sequences: A296782 A296783 A296784 * A296786 A296787 A296788

Keyword

nonn

Author

Eric W. Weisstein, Dec 20 2017

Extensions

Terms a(5) and beyond from Andrew Howroyd, Dec 20 2017

Status

approved