Number of symmetric 11-ary factorizations of the n-cycle (1,2...n).

Terms

a(0) =1a(1) =1a(2) =1a(3) =6a(4) =11a(5) =81a(6) =176a(7) =1406a(8) =3311a(9) =27636a(10) =68211a(11) =585162a(12) =1489488a(13) =13019909a(14) =33870540a(15) =300138696a(16) =793542167a(17) =7105216833a(18) =19022318084a(19) =171717015470a(20) =464333035881