Sum of distinct orders of degree-n permutations.

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =10a(5) =21a(6) =21a(7) =50a(8) =73a(9) =116a(10) =167a(11) =248a(12) =385a(13) =496a(14) =728a(15) =959a(16) =1548a(17) =1899a(18) =2835a(19) =3609a(20) =5042a(21) =6403a(22) =8336a(23) =12187a(24) =15522a(25) =21358a(26) =26090a(27) =35298a(28) =44147a(29) =62512