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%I #4 Mar 30 2012 16:45:52
%S 2,0,0,0,0,4,9,0,9,71,0,0,201,0,175,0,0,2939,19543,0,10841,609483
%N (n,3,2) difference families over Z_n.
%D CRC Handbook of Combinatorial Designs, 1996, p. 285.
%K nonn,hard
%O 7,1
%A _N. J. A. Sloane_.