Number of non-intersecting cycle systems in a particular directed graph.

Terms

a(0) =1a(1) =2a(2) =5a(3) =17a(4) =40a(5) =101a(6) =260a(7) =677a(8) =1768a(9) =4625a(10) =12104a(11) =31685a(12) =82948a(13) =217157a(14) =568520a(15) =1488401a(16) =3896680a(17) =10201637a(18) =26708228a(19) =69923045a(20) =183060904a(21) =479259665a(22) =1254718088a(23) =3284894597a(24) =8599965700a(25) =22515002501a(26) =58945041800