a(n)=least k such that s(k)=n, where s=A030787.

Terms

a(0) =2a(1) =3a(2) =5a(3) =1a(4) =11a(5) =13a(6) =19a(7) =22a(8) =30a(9) =36a(10) =58a(11) =39a(12) =59a(13) =50a(14) =74a(15) =90a(16) =62a(17) =150a(18) =77a(19) =132a(20) =151a(21) =94a(22) =177a(23) =152a(24) =113a(25) =178a(26) =133a(27) =209a(28) =155a(29) =270