A177299 Number of permutations of 4 copies of 1..n with all adjacent differences <= 2 in absolute value.

1, 1, 70, 34650, 4635540, 439192790, 51023044582, 5712786772130, 590059992663400, 59838424359107090

Offset: 0

Author

R. H. Hardin, May 06 2010

Keywords

• nonn
• more

Crossrefs

Cf. A014608.

Formula

a(n) = (4*n)!/24^n for n<=3.

Extensions

a(0), a(9) from Alois P. Heinz, May 30 2025