Number of mobiles (circular rooted trees) on n nodes with thinning limbs.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =10a(6) =24a(7) =47a(8) =113a(9) =258a(10) =624a(11) =1492a(12) =3694a(13) =9090a(14) =22753a(15) =57111a(16) =144541a(17) =367243a(18) =938449a(19) =2406720a(20) =6198045a(21) =16013447a(22) =41507254a(23) =107887092a(24) =281170859a(25) =734518306a(26) =1923119062a(27) =5045423169a(28) =13262334340a(29) =34923020733