a(n) is the smallest term m in A173978 for which A020639(2m-3) = prime(n), n > 1.

Terms

a(0) =6a(1) =19a(2) =40a(3) =106a(4) =112a(5) =265a(6) =220a(7) =427a(8) =625a(9) =730a(10) =871a(11) =1252a(12) =1141a(13) =1717a(14) =2095a(15) =2332a(16) =2716a(17) =2380a(18) =3445a(19) =6097a(20) =4465a(21) =4027a(22) =6187a(23) =6646a(24) =6415a(25) =7675a(26) =6796a(27) =7141a(28) =15991a(29) =8701