cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A249390 The number of down-up permutations of [n] where adjacent elements differ by at least 3.

Original entry on oeis.org

1, 1, 0, 0, 0, 0, 1, 8, 68, 480, 3637, 27968, 231410, 2014784, 18789010, 185234176, 1943243785, 21501237248, 251589065328, 3093350098432, 40007001803593, 541652523341824, 7679190979467688, 113578314941202432
Offset: 0

Views

Author

R. J. Mathar, Oct 27 2014

Keywords

Crossrefs

Cf. A245377 (at least 2), A249391, A249392, A249393, A127697 (non-alternating).

Extensions

a(17)-a(20) from Alois P. Heinz, Oct 27 2014
a(21) from Alois P. Heinz, Oct 28 2014
a(22)-a(23) from Max Alekseyev, Feb 20 2024

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

Original entry on oeis.org

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

Views

Author

R. J. Mathar, Oct 27 2014

Keywords

Crossrefs

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

Extensions

a(17)-a(21) from Alois P. Heinz, Oct 27 2014
a(22)-a(24) from Max Alekseyev, Feb 24 2024

A249393 The number of down-up permutations of [n] where adjacent elements differ by at least 6.

Original entry on oeis.org

1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 64, 4352, 103680, 2644488, 48052224, 922764744, 15466088448, 271484691944, 4512300607488, 78169637107873, 1332149989277696, 23596090882390538
Offset: 0

Views

Author

R. J. Mathar, Oct 27 2014

Keywords

Crossrefs

Cf. A245377 (stride >=2), A249390, A249391, A249392, A179959 (non-alternating).

Extensions

a(19)-a(20) from Alois P. Heinz, Oct 27 2014
a(21) from Alois P. Heinz, Oct 29 2014
a(22)-a(24) from Max Alekseyev, Mar 09 2024
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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