A249391 The number of down-up permutations of [n] where adjacent elements differ by at least 4.

1, 1, 0, 0, 0, 0, 0, 0, 1, 16, 272, 2880, 32648, 333696, 3617545, 38942336, 443291226, 5168682752, 63523977424, 807890646528, 10790865576074, 149552304296960, 2168856599259491, 32631738808727552, 512002155247238968

Offset

0,10

Links

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

Crossrefs

Cf. A245377 (at least 2), A249390 (at least 3), A249392-A249393, A179957 (non-alternating).

Sequence in context: A158574 A330151 A000487 * A197622 A002303 A158610

Adjacent sequences: A249388 A249389 A249390 * A249392 A249393 A249394

Keyword

nonn,more

Author

R. J. Mathar, Oct 27 2014

Extensions

a(17)-a(20) from Alois P. Heinz, Oct 27 2014

a(21)-a(24) from Max Alekseyev, Feb 18 2024

Status

approved