Number of j-sets in symmetric group S_n.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =8a(5) =16a(6) =30a(7) =56a(8) =102a(9) =186a(10) =336a(11) =606a(12) =1088a(13) =1954a(14) =3502a(15) =6278a(16) =11246a(17) =20148a(18) =36086a(19) =64640a(20) =115774a(21) =207374a(22) =371430a(23) =665298a(24) =1191646a(25) =2134454a(26) =3823160a(27) =6847974a(28) =12265912a(29) =21970470