A189953 - OEIS

%I #5 Mar 31 2012 12:36:16

%S 4,22,63,159,306,542,889,1350,1940,2734,3670,4819,6238,7852,9688,

%T 11986,14411,17274,20412,23919,27900,32443,37028,42280,48028,54459,

%U 60919,68477,76078,84753,93786,103538,113637,125008,136030,149100,162115,176241

%N 1/4 the number of arrangements of 4 nonzero numbers x(i) in -n..n with the sum of sign(x(i))*(|x(i)| mod x(i+1)) equal to zero

%C Row 3 of A189951

%H R. H. Hardin, <a href="/A189953/b189953.txt">Table of n, a(n) for n = 1..200</a>

%e Some solutions with n=3

%e ..1....3....1....2...-2....2....3....1...-1....2...-3...-1...-3...-1....1....3

%e .-3...-3...-3...-2....2...-2....1....1...-1....2...-3....3....2....2...-2....3

%e .-3...-3....2...-2...-1....2...-3....1....1...-1...-3....2....1....1...-1...-3

%e ..2....1...-2...-2...-1....2...-2....1...-1...-1...-1....2....3...-3....3...-1

%K nonn

%O 1,1

%A _R. H. Hardin_ May 02 2011