1,3
Cf. A088310.
Sequence in context: A175672 A181749 A181232 * A158042 A147860 A159409
Adjacent sequences: A088613 A088614 A088615 * A088617 A088618 A088619
nonn
Yuval Dekel and Vladeta Jovovic, Nov 17 2003
What if you also ask that the two main diagonals are also distinct? - N. J. A. Sloane (njas(AT)research.att.com), Jan 03 2004.