a(n) = 2i + 1 where i is the least index such that A039508(i) = n or 0 if there is none.

Terms

a(0) =1a(1) =7a(2) =11a(3) =23a(4) =29a(5) =5a(6) =187a(7) =25a(8) =35a(9) =13a(10) =55a(11) =125a(12) =145a(13) =91a(14) =143a(15) =65a(16) =247a(17) =175a(18) =269a(19) =233a(20) =745a(21) =517a(22) =485a(23) =431a(24) =1547a(25) =455a(26) =1645a(27) =715a(28) =943a(29) =295