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A053623
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Number of distinct non-extendable sequences (x(1),x(2),...,x(k)) such that each x(i) is in {1,2,...,n} and (x(j) AND x(i)) <> x(j) for i=2..k, j=1..i-1.
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2
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1, 2, 4, 14, 38, 126, 252, 1662, 7180, 39430, 111064, 803876, 2863992, 12123360, 24246720, 329012784, 2602608516
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OFFSET
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1,2
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REFERENCES
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Related to Mathematical Recreations, Scientific American, March 2000.
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LINKS
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EXAMPLE
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a(3)=4, since the allowable sequences are (1,2), (2,1), (3,1,2), (3,2,1).
(1,3) is not allowed because 1 AND 3 = 01 AND 11 (base 2) = 1.
(3,1) is not allowed because it can be extended to (3,1,2).
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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