A048893 Threshold function for orthogonal arrays of strength 2.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 6, 12, 13, 14, 15, 16, 15, 18, 11, 20, 21, 22

Offset

1,3

Comments

a(n) = max b such that any parameter set satisfying the obvious necessary conditions and with <= b degrees of freedom exists, but some such parameter set with b+1 degrees of freedom does not exist.

Links

Table of n, a(n) for n=1..23.

E. M. Rains, N. J. A. Sloane and J. Stufken, The Lattice of N-Run Orthogonal Arrays, J. Stat. Planning Inference, 102 (2002), 477-500 (Abstract, pdf, ps)

Crossrefs

Cf. A048894, A048885.

Sequence in context: A286603 A291751 A275987 * A330814 A305903 A305904

Adjacent sequences: A048890 A048891 A048892 * A048894 A048895 A048896

Keyword

nonn

Author

N. J. A. Sloane, John Stufken (jstufken(AT)iastate.edu)

Extensions

18<=a(24)<=22 is the first open case. Sequence then continues 24,25,26,15,28,29,30,29.

Status

approved