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A361295
A variant of payphone permutations: given a row of n payphones, a(n) is the number ways for n people to choose the payphones in order, where each person chooses an unoccupied payphone such that the closest occupied payphone is as distant as possible, and among the available payphones adjacent to a single occupied payphone the most preferred are payphones at open ends.
6
1, 2, 4, 6, 12, 40, 144, 384, 1008, 6816, 33600, 115200, 783360, 3024000, 16450560, 140636160, 558351360, 2262435840, 29599395840, 180278784000, 2124328550400, 13664957644800, 127667338444800, 852837440716800, 11377123378790400, 116737211695104000, 816490952589312000
OFFSET
1,2
LINKS
Max A. Alekseyev, Enumeration of Payphone Permutations, arXiv:2304.04324 [math.CO], 2023.
KEYWORD
nonn
AUTHOR
Max Alekseyev, Apr 08 2023
EXTENSIONS
Definition corrected by Max Alekseyev, Jun 21 2023
STATUS
approved