s(n)=2, where s=A030777.

Terms

a(0) =3a(1) =9a(2) =18a(3) =25a(4) =28a(5) =34a(6) =35a(7) =44a(8) =57a(9) =60a(10) =72a(11) =75a(12) =89a(13) =92a(14) =108a(15) =111a(16) =128a(17) =131a(18) =150a(19) =174a(20) =181a(21) =201a(22) =205a(23) =207a(24) =208a(25) =231a(26) =266a(27) =269a(28) =274a(29) =275