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A048893 Threshold function for orthogonal arrays of strength 2. 1
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 6, 12, 13, 14, 15, 16, 15, 18, 11, 20, 21, 22 (list; graph; refs; listen; history; text; internal format)
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 * A305903 A305904 A319345

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

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Last modified October 19 22:28 EDT 2018. Contains 316378 sequences. (Running on oeis4.)