A212268 Number of circular permutations of 1..n with no adjacent three summing to a prime, ignoring rotations and reversals

0, 0, 1, 0, 2, 4, 14, 48, 432, 2316, 24743, 223506, 2537594, 26771235, 344781871, 3927465497, 53273396228, 660418431957

Offset

1,5

Links

Table of n, a(n) for n=1..18.

Example

Some solutions for n=8
..5....6....4....2....2....5....5....6....3....3....4....2....2....5....2....2
..1....1....1....1....1....1....1....1....1....1....1....1....1....1....1....1
..6....7....7....7....3....8....8....7....8....6....7....7....3....6....6....5
..8....2....6....6....4....3....7....8....7....8....6....8....4....7....8....4
..4....5....2....8....5....7....6....5....5....2....8....6....8....3....4....6
..3....3....8....4....7....2....2....3....6....5....2....4....6....4....3....8
..7....4....5....3....8....6....4....4....4....7....5....5....7....2....7....7
..2....8....3....5....6....4....3....2....2....4....3....3....5....8....5....3

Crossrefs

Sequence in context: A102879 A032312 A032222 * A092665 A046650 A327235

Adjacent sequences: A212265 A212266 A212267 * A212269 A212270 A212271

Keyword

nonn

Author

R. H. Hardin May 12 2012

Status

approved