%I #5 Mar 31 2012 12:36:11

%S 1,4,12,52,221,1019,4818,23522,117209,594789,3062414,15966168,

%T 84132345,447457816,2399177028,12956403904,70416558196,384897011042,

%U 2114694606220,11672750655842,64705139473661,360068911514032,2010827078176568

%N Number of nondecreasing arrangements of n numbers in -(n+1)..(n+1) with sum zero and not more than two numbers equal

%C Column 3 of A188236

%H R. H. Hardin, <a href="/A188230/b188230.txt">Table of n, a(n) for n = 1..30</a>

%e Some solutions for n=4

%e .-3...-5...-5...-3...-3...-1...-4...-5...-4...-4...-2...-5...-4...-4...-4...-3

%e .-2...-5....0...-3....0...-1....1...-1...-2...-4...-2...-3...-1...-3...-3...-1

%e ..1....5....1....2....1....0....1....2....2....3....1....3....2....2....3....2

%e ..4....5....4....4....2....2....2....4....4....5....3....5....3....5....4....2

%K nonn

%O 1,2

%A _R. H. Hardin_ Mar 24 2011