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A048893
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Threshold function for orthogonal arrays of strength 2.
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1
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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; internal format)
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OFFSET
| 1,3
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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.
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LINKS
| 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)
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CROSSREFS
| Cf. A048894, A048885.
Sequence in context: A064698 A094175 A171060 * A073835 A051503 A179622
Adjacent sequences: A048890 A048891 A048892 * A048894 A048895 A048896
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), John Stufken (jstufken(AT)iastate.edu)
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EXTENSIONS
| 18<=a(24)<=22 is the first open case. Sequence then continues 24,25,26,15,28,29,30,29.
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