Number of primes of the form x^2 + 1 < 10^n.

Terms

a(0) =2a(1) =4a(2) =10a(3) =19a(4) =51a(5) =112a(6) =316a(7) =841a(8) =2378a(9) =6656a(10) =18822a(11) =54110a(12) =156081a(13) =456362a(14) =1339875a(15) =3954181a(16) =11726896a(17) =34900213a(18) =104248948a(19) =312357934a(20) =938457801a(21) =2826683630a(22) =8533327397a(23) =25814570672a(24) =78239402726a(25) =237542444180a(26) =722354138859