A370961 a(n) = number of acyclic orientations of the complete tripartite graph K_{n,n,n}.

1, 6, 426, 122190, 90768378, 138779942046, 379578822373866, 1689637343582548590, 11434884125767376107098, 111765072808554847704145086, 1515592947854931941485836600906, 27609710924806869786487193747541390, 658043992934027491354757341987635993018

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..155 (terms n = 1..16 from Don Knuth)

Don Knuth, Parades and poly-Bernoulli bijections, Mar 31 2024. See (19.2).

Formula

a(n) = A266858(3n) = A267383(3n,3). - Alois P. Heinz, Apr 17 2024

a(n) = Sum_{k=0..3n} (-1)^k * A212220(n,k). - Alois P. Heinz, May 02 2024

Crossrefs

Cf. A212220, A266858, A267383, A370960.

Main diagonal of A372254.

Row n=3 of A372326.

Sequence in context: A199253 A199198 A000410 * A275686 A173760 A269882

Adjacent sequences: A370958 A370959 A370960 * A370962 A370963 A370964

Keyword

nonn,changed

Author

N. J. A. Sloane, Apr 04 2024

Extensions

More terms from Don Knuth, Apr 07 2024

a(0)=1 prepended by Alois P. Heinz, Apr 17 2024

Status

approved