Number of 6-covers of an unlabeled n-set.

Terms

a(0) =1a(1) =6a(2) =43a(3) =336a(4) =2864a(5) =25326a(6) =223034a(7) =1890123a(8) =15115098a(9) =112980937a(10) =787320629a(11) =5121184083a(12) =31188412225a(13) =178517111561a(14) =964196387369