• #### Permutations of (1, 2, ..., N) s.t. No adjacent Numbers are ...

From henhanna@gmail.com@21:1/5 to All on Sat Nov 5 18:58:20 2022
i wonder if there's any chance that oeis doesn't mention this.

1 --> 0
2 --> 0
3 --> 0
4 --> 8 ? (probably more)

N --> f(N)

the Number of Permutations of (1, 2, ..., N)
in which No adjacent Numbers are diff. by 1.

A good Jumble-generator prob. does this... (== separate original neighbors).

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• From Ilan Mayer@21:1/5 to henh...@gmail.com on Sun Nov 6 07:38:07 2022
On Saturday, November 5, 2022 at 9:58:21 PM UTC-4, henh...@gmail.com wrote:
i wonder if there's any chance that oeis doesn't mention this.

1 --> 0
2 --> 0
3 --> 0
4 --> 8 ? (probably more)

N --> f(N)

the Number of Permutations of (1, 2, ..., N)
in which No adjacent Numbers are diff. by 1.

A good Jumble-generator prob. does this... (== separate original neighbors).

https://oeis.org/A002464

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• From henhanna@gmail.com@21:1/5 to Ilan Mayer on Sun Nov 6 11:06:30 2022
On Sunday, November 6, 2022 at 7:38:09 AM UTC-8, Ilan Mayer wrote:
On Saturday, November 5, 2022 at 9:58:21 PM UTC-4, henh...@gmail.com wrote:
i wonder if there's any chance that oeis doesn't mention this.

1 --> 0
2 --> 0
3 --> 0
4 --> 8 ? (probably more)

N --> f(N)

the Number of Permutations of (1, 2, ..., N)
in which No adjacent Numbers are diff. by 1.

A good Jumble-generator prob. does this... (== separate original neighbors).

https://oeis.org/A002464

thansk!

Hertzsprung's problem: ways to arrange n non-attacking kings on an n X n board, with 1 in each row and column. Also number of permutations of length n without rising or falling successions.
(Formerly M2070 N0818)
1, 1, 0, 0, 2, 14, 90, 646, 5242, 47622, 479306, 5296790, 63779034, 831283558, 11661506218,

How did they get 2 ?

2413, (and its reverse) ------- omg.. that is 2

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