Smallest number with exactly n prime substrings.

Terms

a(0) =1a(1) =2a(2) =13a(3) =23a(4) =113a(5) =137a(6) =373a(7) =1137a(8) =1733a(9) =1373a(10) =11317a(11) =11373a(12) =13733a(13) =31373a(14) =113173a(15) =131373a(16) =137337a(17) =337397a(18) =1113173a(19) =1137337a(20) =1373373a(21) =2337397a(22) =3733797a(23) =11373137a(24) =11373379a(25) =13733797a(26) =37337397a(27) =111373379a(28) =123733739