a(n)=least k such that s(k)=n, where s=A030747.

Terms

a(0) =2a(1) =4a(2) =5a(3) =1a(4) =8a(5) =12a(6) =20a(7) =17a(8) =23a(9) =34a(10) =52a(11) =31a(12) =54a(13) =40a(14) =66a(15) =81a(16) =51a(17) =139a(18) =63a(19) =115a(20) =136a(21) =78a(22) =160a(23) =137a(24) =95a(25) =159a(26) =114a(27) =183a(28) =134a(29) =245