Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #10 Oct 26 2023 08:26:09
%S 1,14,19164,6941592576
%N Acyclic orientations of Hamming graph (K_n) x (K_n).
%C 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 Martin Harborth, Structural analysis of shop scheduling problems, PhD thesis, Otto-von-Guericke-Univ. Magdeburg, GCA-Verlag, 1999. (in German)
%H H. Bräsel, M. Harborth, T. Tautenhahn and P. Willenius, <a href="https://doi.org/10.1023/A:1018938915709">On the set of solutions of the open shop problem</a>, Ann. Oper. Res. 92 (1999) 241-263.
%K nonn,nice,hard,more
%O 1,2
%A Martin Harborth (Martin.Harborth(AT)vt.siemens.de)