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A213270
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Costas arrays such that the corresponding permutation is an involution.
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4
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1, 2, 2, 2, 4, 10, 20, 18, 20, 28, 36, 34, 50, 46, 62, 40, 38, 20, 12, 8, 16, 10, 20, 0, 4, 4, 14, 0, 10
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OFFSET
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1,2
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COMMENTS
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Self-inverse permutations such that each row in the difference table consists of pairwise distinct elements (see example).
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LINKS
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EXAMPLE
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The permutation (4, 7, 9, 1, 6, 5, 2, 8, 3) is an involution and corresponds to a Costas array:
4 7 9 1 6 5 2 8 3 (Permutation: p(1), p(2), p(3), ..., p(n) )
3 2 -8 5 -1 -3 6 -5 (step-1 differences: p(2)-p(1), p(3)-p(2), ... )
5 -6 -3 4 -4 3 1 (step-2 differences: p(3)-p(1), p(4)-p(2), ... )
-3 -1 -4 1 2 -2 (step-3 differences: p(4)-p(1), p(5)-p(2), ... )
2 -2 -7 7 -3 ( etc. )
1 -5 -1 2
-2 1 -6
4 -4
-1
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CROSSREFS
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Cf. A008404 (Costas arrays), A213271 (Costas arrays that are derangements), A213338 (Costas arrays that are cyclic), A213339 (Costas arrays that are connected).
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KEYWORD
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nonn,hard,more
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AUTHOR
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STATUS
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approved
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