A182540 Number of ways of arranging the numbers 1 through n on a circle so that no sum of two adjacent numbers is prime, up to rotations and reflections.

0, 0, 0, 0, 0, 1, 6, 44, 208, 912, 8016, 61952, 671248, 8160620, 87412258, 888954284, 12156253488, 180955852060, 2907927356451, 50317255621843, 802326797235038, 12251146829850324, 233309934271940028, 4243527581615332664, 79533825261873435894, 1602629887788636447221, 30450585799991840921483, 622433536382831426225696, 14891218890120375419560713, 344515231090957672408413959

Offset

1,7

Links

Table of n, a(n) for n=1..30.

Example

If n < 6, then in every arrangement of the numbers 1 through n on a circle, there are two adjacent numbers adding up to a prime. For n = 6, the only arrangement without a prime sum is (1, 3, 6, 2, 4, 5).

Crossrefs

Cf. A051252, A073452, A191374

Sequence in context: A000561 A292057 A258156 * A309418 A203601 A091162

Adjacent sequences: A182537 A182538 A182539 * A182541 A182542 A182543

Keyword

nonn

Author

Jens Voß, May 04 2012

Extensions

a(15)-a(17) from Alois P. Heinz, May 04 2012

a(18) from R. H. Hardin, May 07 2012

a(19)-a(30) from Max Alekseyev, Aug 19 2013

Status

approved