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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.

A040018 (Number of permutations of {1,2,...,n} for which sums of adjacent numbers are all distinct)/2n.

Original entry on oeis.org

1, 1, 3, 8, 46, 176, 955, 5446, 36122, 259084, 2043944, 17371318, 159616680, 1566391958
Offset: 3

Views

Author

Erich Friedman

Keywords

Comments

Essentially different ways 1,2,3,...,n can be placed around a circle so that sums of adjacent numbers are distinct.

Links

Crossrefs

Cf. A091217, A006967.

Extensions

a(10) from Vladeta Jovovic, Aug 25 2007
a(11)-a(13) from Steve Butler, Feb 08 2012
a(14)-a(16) from Sean A. Irvine, Mar 05 2021

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