a(n) = index of 2*prime(n) in A381019.

Terms

a(0) =7a(1) =23a(2) =47a(3) =79a(4) =123a(5) =223a(6) =325a(7) =364a(8) =630a(9) =910a(10) =1034a(11) =1310a(12) =1610a(13) =1857a(14) =2219a(15) =2819a(16) =3378a(17) =3979a(18) =4499a(19) =4773a(20) =5057a(21) =5790a(22) =6899a(23) =7581a(24) =9226a(25) =9429a(26) =10225a(27) =11459a(28) =12329a(29) =12781