A182540 - OEIS

%I #25 Sep 08 2013 11:22:54

%S 0,0,0,0,0,1,6,44,208,912,8016,61952,671248,8160620,87412258,

%T 888954284,12156253488,180955852060,2907927356451,50317255621843,

%U 802326797235038,12251146829850324,233309934271940028,4243527581615332664,79533825261873435894,1602629887788636447221,30450585799991840921483,622433536382831426225696,14891218890120375419560713,344515231090957672408413959

%N 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.

%e 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).

%Y Cf. A051252, A073452, A191374

%K nonn

%O 1,7

%A _Jens Voß_, May 04 2012

%E a(15)-a(17) from _Alois P. Heinz_, May 04 2012

%E a(18) from _R. H. Hardin_, May 07 2012

%E a(19)-a(30) from _Max Alekseyev_, Aug 19 2013