A014767 - OEIS

%I #10 Aug 14 2022 16:43:21

%S 1,2,6,12,60,120,5040,32,181440,3628800,39916800,95040,3113510400,

%T 87178291200,1307674368000,80,177843714048000,6402373705728000,

%U 121645100408832000,1216451004088320000,25545471085854720000

%N Order of shuffle group on n cards {0..n-1} generated by i->n-1-i and i->min{2i,2n-1-2i}.

%D J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 323.

%o (Magma) S := function(n) G := Sym({0..n-1}); p := &*[ G | (i, n-1-i) : i in [ 0..Floor((n-2)/2) ] ];

%o q := G![ Min(2*i,2*n-1-2*i):i in [ 0..n-1 ] ]; return Order(sub<G | p, q >); end function;

%K nonn,easy,nice

%O 1,2

%A _N. J. A. Sloane_