Self-composition of the Dedekind psi function (A001615).

Terms

a(0) =1a(1) =6a(2) =26a(3) =99a(4) =348a(5) =1194a(6) =4000a(7) =13326a(8) =44058a(9) =144066a(10) =462504a(11) =1459194a(12) =4545588a(13) =14068554a(14) =43450848a(15) =134213808a(16) =414692130a(17) =1280610858a(18) =3948172380a(19) =12142365042a(20) =37235047770a(21) =113844652986a(22) =347103133068