A297487 Number of maximal matchings in the complete tripartite graph K_n,n,n.

3, 14, 342, 5256, 252360, 7950960, 582346800, 30400755840, 3055726477440, 234650484230400, 30479146156166400, 3193083216360576000, 515174657767010841600, 69927761804930559129600, 13622234004598726450944000, 2307722078006148475736064000

Offset

1,1

Links

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

Eric Weisstein's World of Mathematics, Complete Tripartite Graph

Eric Weisstein's World of Mathematics, Matching

Eric Weisstein's World of Mathematics, Maximal Independent Edge Set

Mathematica

Table[3 n! HypergeometricPFQ[{(1 - n)/2, -n, -n/2}, {1}, -4] - If[Mod[n, 2] == 0, 2 (n!/(n/2)!)^3, 0], {n, 20}]

Prog

(PARI) a(n)={if(n%2==0, binomial(n, n/2)*(n/2)!, 0)^3 + sum(k=0, (n-1)\2, 3*binomial(n, k)^2*binomial(n, 2*k)*binomial(2*k, k)*k!^2*(n-k)!)} \\ Andrew Howroyd, Dec 30 2017

Crossrefs

Cf. A293075.

Sequence in context: A144985 A168590 A309028 * A297484 A289878 A081397

Adjacent sequences: A297484 A297485 A297486 * A297488 A297489 A297490

Keyword

nonn

Author

Eric W. Weisstein, Dec 30 2017

Extensions

Terms a(6) and beyond from Andrew Howroyd, Dec 30 2017

Status

approved