%I #4 Mar 30 2012 16:45:52

%S 2,4,0,3,21,0,180,253,0,2981,21742,0,320760

%N (n,3,4) difference families over Z_n.

%D CRC Handbook of Combinatorial Designs, 1996, p. 285.

%K nonn,hard

%O 6,1

%A _N. J. A. Sloane_.