A177600 Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, down.

1, 1, 20, 1680, 354624, 151213748, 114062310060, 139028830444866, 256400413791435360, 680598969845995094212, 2500271405904975564019712

Offset: 0

Author

R. H. Hardin, May 10 2010

Keywords

• nonn

Crossrefs

Cf. A014606.

Extensions

a(9)-a(10) from Alois P. Heinz, Nov 02 2013