Number of n-covers of an unlabeled 5-set.

Terms

a(0) =1a(1) =12a(2) =103a(3) =736a(4) =4571a(5) =25326a(6) =127415a(7) =588687a(8) =2518997a(9) =10053739a(10) =37656707a(11) =133084998a(12) =445949359a(13) =1422934989a(14) =4340110439a(15) =12697803333a(16) =35744330644a(17) =97081519369a(18) =255032046536a(19) =649459943602