First prime not the middle of a prime two digits longer in base n.

Terms

a(0) =3a(1) =7a(2) =19a(3) =97a(4) =823a(5) =3499a(6) =2777a(7) =6827a(8) =2437a(9) =21523a(10) =300299a(11) =446273a(12) =339769a(13) =1168523a(14) =14117417a(15) =29227421a(16) =14160061a(17) =78521987a(18) =161187707a(19) =1200085823a(20) =2125209127a(21) =1369430897a(22) =56378083771a(23) =26054006611a(24) =76375900241a(25) =290373503549a(26) =640442460709