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Number of arrangements of n+1 nonzero numbers x(i) in -2..2 with the sum of div(x(i),x(i+1)), where div(a,b)=a/b produces the integer quotient implying a nonnegative remainder, equal to zero
1

%I #5 Mar 31 2012 12:36:19

%S 2,12,40,144,550,1896,7584,27328,105348,398760,1538696,5872800,

%T 22646862,87492676,339055650,1313842904,5104724558,19873572892,

%U 77470783406,302258087616,1180840902336,4618922848536,18083348822516,70852652846320

%N Number of arrangements of n+1 nonzero numbers x(i) in -2..2 with the sum of div(x(i),x(i+1)), where div(a,b)=a/b produces the integer quotient implying a nonnegative remainder, equal to zero

%C Column 2 of A190071

%H R. H. Hardin, <a href="/A190064/b190064.txt">Table of n, a(n) for n = 1..200</a>

%e Some solutions for n=4

%e .-2...-1...-1...-2...-2....1....2...-1...-1....2...-2....1....2....2....1....1

%e .-2....1....1...-1...-1...-1....1....1...-2...-1....1....1...-1....2...-2....1

%e ..2....1...-2....1....1...-1....2....2....1...-2....1....2....2....2....1....1

%e .-2...-1....2....2...-2....2...-2...-2....1....2....1...-1....1...-2....2...-1

%e .-2...-2....1...-2....2....2....2...-1....2....1....2...-1....1....2....1....1

%K nonn

%O 1,1

%A _R. H. Hardin_ May 04 2011