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A208727 T(n,k)=Number of 2n-bead necklaces labeled with numbers 1..k not allowing reversal, with neighbors differing by exactly 1. 8
0, 1, 0, 2, 1, 0, 3, 3, 1, 0, 4, 5, 4, 1, 0, 5, 7, 8, 6, 1, 0, 6, 9, 12, 15, 8, 1, 0, 7, 11, 16, 25, 27, 14, 1, 0, 8, 13, 20, 35, 52, 60, 20, 1, 0, 9, 15, 24, 45, 78, 131, 123, 36, 1, 0, 10, 17, 28, 55, 104, 210, 316, 285, 60, 1, 0, 11, 19, 32, 65, 130, 290, 551, 835, 648, 108, 1, 0, 12, 21, 36 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Table starts

.0.1..2...3...4....5....6....7....8....9...10...11...12..13..14..15.16.17.18

.0.1..3...5...7....9...11...13...15...17...19...21...23..25..27..29.31.33

.0.1..4...8..12...16...20...24...28...32...36...40...44..48..52..56.60

.0.1..6..15..25...35...45...55...65...75...85...95..105.115.125.135

.0.1..8..27..52...78..104..130..156..182..208..234..260.286.312

.0.1.14..60.131..210..290..370..450..530..610..690..770.850

.0.1.20.123.316..551..796.1042.1288.1534.1780.2026.2272

.0.1.36.285.835.1569.2366.3175.3985.4795.5605.6415

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..183

EXAMPLE

All solutions for n=5, k=3:

..2....1....1....1....1....1....1....1

..3....2....2....2....2....2....2....2

..2....3....1....1....1....3....1....1

..3....2....2....2....2....2....2....2

..2....1....1....3....1....3....3....1

..3....2....2....2....2....2....2....2

..2....3....1....3....3....3....1....1

..3....2....2....2....2....2....2....2

..2....3....3....3....3....3....3....1

..3....2....2....2....2....2....2....2

CROSSREFS

Column 3 is A000031.

Cf. A198632, A232441, A186740.

Sequence in context: A122285 A100224 A208671 * A242378 A268820 A199011

Adjacent sequences:  A208724 A208725 A208726 * A208728 A208729 A208730

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin, Mar 01 2012

STATUS

approved

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Last modified December 12 07:00 EST 2019. Contains 329948 sequences. (Running on oeis4.)