Number of n-covers of an unlabeled 3-set.

Terms

a(0) =1a(1) =6a(2) =23a(3) =65a(4) =156a(5) =336a(6) =664a(7) =1229a(8) =2159a(9) =3629a(10) =5877a(11) =9221a(12) =14070a(13) =20951a(14) =30530a(15) =43634a(16) =61283a(17) =84725a(18) =115461a(19) =155294a(20) =206368a(21) =271210a(22) =352784a(23) =454550a(24) =580509a(25) =735280a(26) =924163a(27) =1153207a(28) =1429292a(29) =1760218