A177298 Number of permutations of 4 copies of 1..n with all adjacent differences <= 1 in absolute value.

1, 1, 70, 780, 11482, 135040, 1543862, 16699380, 175280570, 1792874048, 17990831182, 177773616180, 1735220375914, 16769137076968, 160740670148270, 1530462874512756, 14491157235576770, 136575590461035368, 1282229192334549022, 11999276440029403356, 111987255233226452770

Offset: 0

Author

R. H. Hardin, May 06 2010

Keywords

• nonn

Comments

a(n) = (4n)!/24^n = A014608(n) for n<=2.

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..200

Crossrefs

Cf. A014608.

Column k=4 of A331562.

Extensions

a(0)=1 prepended by Alois P. Heinz, Jan 20 2020

a(12)-a(13) from Alois P. Heinz, Jan 21 2020

Terms a(14) and beyond from Andrew Howroyd, May 15 2020