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 A216797 Number of permutations of an n X 5 array with each element moving exactly one horizontally or vertically and without 2-loops. 2

%I #8 Mar 09 2018 10:44:25

%S 0,10,0,292,0,10140,0,361200,0,12911864,0,461788640,0,16516859104,0,

%T 590766585904,0,21130267285488,0,755777826856944,0,27032319708816080,

%U 0,966879797484085808,0,34582919761038885136,0,1236946249622251150000,0

%N Number of permutations of an n X 5 array with each element moving exactly one horizontally or vertically and without 2-loops.

%C Column 5 of A216800.

%H R. H. Hardin, <a href="/A216797/b216797.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 49*a(n-2) - 524*a(n-4) + 1862*a(n-6) - 1728*a(n-8).

%F Empirical g.f.: 2*x^2*(5 - 99*x^2 + 536*x^4 - 636*x^6) / (1 - 49*x^2 + 524*x^4 - 1862*x^6 + 1728*x^8). - _Colin Barker_, Mar 09 2018

%e Some solutions for n=4:

%e ..1..2..7..8..3....5..0..1..4..9....5..0..3..4..9....1..6..7..2..3

%e ..0..5..6..9..4...10..7..2..3.14....6..1..2.13..8....0..5..8..9..4

%e .11.12.13.14.19...15..6.13..8.19...11.12..7.14.19...15.10.11.14.19

%e .10.15.16.17.18...16.11.12.17.18...10.15.16.17.18...16.17.12.13.18

%Y Cf. A216800.

%K nonn

%O 1,2

%A _R. H. Hardin_, Sep 17 2012

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Last modified September 22 03:20 EDT 2023. Contains 365503 sequences. (Running on oeis4.)