A249392 The number of down-up permutations of [n] where adjacent elements differ by at least 5.

1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 32, 1088, 17280, 293832, 4004352, 57687080, 773838336, 10900027949, 151388845568, 2200665880514, 32321771402240, 495575856116168, 7760560549644288, 126552637539515688

Offset

0,12

Links

Table of n, a(n) for n=0..24.

Crossrefs

Cf. A245377 (at least 2), A249390 (at least 3), A249391 (at least 4), A249393 (at least 6), A179958 (non-alternating)

Sequence in context: A158685 A265021 A159360 * A114933 A038097 A208267

Adjacent sequences: A249389 A249390 A249391 * A249393 A249394 A249395

Keyword

nonn,more

Author

R. J. Mathar, Oct 27 2014

Extensions

a(17)-a(21) from Alois P. Heinz, Oct 27 2014

a(22)-a(24) from Max Alekseyev, Feb 24 2024

Status

approved