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 A208667 Number of 2n-bead necklaces labelled with numbers 1..4 allowing reversal, with neighbors differing by exactly 1 0
 3, 5, 8, 14, 24, 47, 89, 187, 396, 881, 1990, 4645, 10935, 26211, 63320, 154378, 378444, 933023, 2308957, 5735372, 14286908, 35683815, 89324138, 224057919 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 4 of A208671 LINKS EXAMPLE All solutions for n=4 ..1....2....2....2....1....1....1....1....1....3....1....1....2....2 ..2....3....3....3....2....2....2....2....2....4....2....2....3....3 ..1....2....2....2....1....1....3....3....3....3....3....1....4....4 ..2....3....3....3....2....2....4....2....2....4....2....2....3....3 ..1....4....2....2....3....1....3....1....3....3....3....3....2....4 ..2....3....3....3....4....2....4....2....4....4....2....2....3....3 ..1....4....2....4....3....3....3....3....3....3....3....3....4....4 ..2....3....3....3....2....2....2....2....2....4....2....2....3....3 CROSSREFS Sequence in context: A109022 A023596 A086661 * A078065 A175378 A072655 Adjacent sequences:  A208664 A208665 A208666 * A208668 A208669 A208670 KEYWORD nonn AUTHOR R. H. Hardin Feb 29 2012 STATUS approved

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Last modified May 22 05:06 EDT 2013. Contains 225511 sequences.