%I A053870
%S A053870 1,14,19164,6941592576
%N A053870 Acyclic orientations of Hamming graph (K_n) x (K_n).
%C A053870 This number is equivalent to the number of plans (i.e. structural solutions) 
               of the open shop problem with n jobs and n machines - see problems 
               in scheduling theory.
%D A053870 H. Braesel, M. Harborth, T. Tautenhahn and P. Willenius, On the set of 
               solutions of the open shop problem, Ann. Oper. Res. 92 (1999) 241-263
%D A053870 M. Harborth, Structural analysis of shop scheduling problems, PhD thesis, 
               Otto-von-Guericke-Univ. Magdeburg, GCA-Verlag, 1999 (in German)
%Y A053870 Sequence in context: A147686 A048913 A104376 this_sequence A079176 A013754 
               A073940
%Y A053870 Adjacent sequences: A053867 A053868 A053869 this_sequence A053871 A053872 
               A053873
%K A053870 nonn,nice,hard
%O A053870 1,2
%A A053870 Martin Harborth (Martin.Harborth(AT)vt.siemens.de)