

A208666


Number of 2nbead necklaces labeled with numbers 1..n allowing reversal, with neighbors differing by exactly 1.


1



0, 1, 4, 14, 44, 152, 514, 1866, 6884, 26137, 100442, 390592, 1526272, 5989223, 23548688, 92727898, 365445200, 1441195226, 5686268314, 22444465311, 88622259788, 350040069245, 1383007946774, 5465854718664, 21607909105528, 85444555330132, 337962745845558, 1337094537703089
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OFFSET

1,3


LINKS



FORMULA



EXAMPLE

All solutions for n=3:
..1....1....1....2
..2....2....2....3
..1....3....1....2
..2....2....2....3
..3....3....1....2
..2....2....2....3


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



