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A206478 (Number of permutations of {1,2,...,n} for which sums of four consecutive numbers (with wraparound) are all distinct)/2n 0
12, 8, 76, 694, 2529, 23679, 177885, 1482021, 14666021 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,1

COMMENTS

Essentially different ways that 1,2,...,n can be placed around a circle so that the sums of three consecutive terms are all distinct.

LINKS

Table of n, a(n) for n=5..13.

EXAMPLE

a(6)=8 because up to rotation/reflection the only three permutations which work are 123465, 123546, 124653, 125364, 126543, 132456, 132645, 136524.

CROSSREFS

Cf. A040018

Sequence in context: A307171 A040134 A258641 * A164675 A121961 A168386

Adjacent sequences:  A206475 A206476 A206477 * A206479 A206480 A206481

KEYWORD

hard,nonn

AUTHOR

Steve Butler, Feb 08 2012

STATUS

approved

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Last modified November 11 15:46 EST 2019. Contains 329018 sequences. (Running on oeis4.)