Number of functions on n unlabeled nodes in which all the components are distinct.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =14a(5) =38a(6) =103a(7) =280a(8) =773a(9) =2160a(10) =6053a(11) =17064a(12) =48320a(13) =137260a(14) =391091a(15) =1117192a(16) =3198217a(17) =9173480a(18) =26357393a(19) =75845591a(20) =218550709a(21) =630536447a(22) =1821184411a(23) =5265514692a(24) =15238183779a(25) =44136519841a(26) =127940010907a(27) =371135327740