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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A117541 Number of permutations P of 1..n such that in P and in the inverse of P, every pair of adjacent numbers are relatively prime.

Original entry on oeis.org

1, 2, 6, 9, 56, 23, 399, 442, 2220, 2386, 71577, 22001, 1179483, 1156519, 4975079
Offset: 1

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Author

Giovanni Resta, Mar 28 2006

Keywords

Comments

Sequence suggested by Leroy Quet on the SeqFan mailing list.

Examples

			a(4)=9, since the 9 permutations (1,2,3,4), (1,4,3,2), (2,1,3,4), (2,1,4,3), (2,3,4,1), (4,1,2,3), (3,2,1,4), (3,4,1,2), (4,3,2,1) satisfy the property.

Crossrefs

Cf. A076220, A117542.
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