Number of emirps of length ceiling(n/4)+1 and leading digit 1, 3, 7 or 9 (in sequence).

Terms

a(0) =2a(1) =2a(2) =3a(3) =1a(4) =7a(5) =5a(6) =8a(7) =8a(8) =60a(9) =51a(10) =43a(11) =50a(12) =388a(13) =350a(14) =322a(15) =345a(16) =2632a(17) =2422a(18) =2253a(19) =2231a(20) =18770a(21) =17751a(22) =17066a(23) =16887a(24) =141594a(25) =134894a(26) =130276a(27) =128814a(28) =1105560a(29) =1058667