A188349 - OEIS

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

%S 5,45,257,4201,45801,1171345,25217201,870473329,30807035021,

%T 1370460938381

%N Number of arrangements of n+1 numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero

%C Diagonal of A188358

%e Some solutions for n=4

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

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ Mar 28 2011