a(1)=4, then least semiprime > a(n-1) such that when all in the sequence are concatenated together they form a prime.

A085703

a(1)=4, then least semiprime > a(n-1) such that when all in the sequence are concatenated together they form a prime.

Terms

    a(0) =4a(1) =21a(2) =39a(3) =49a(4) =93a(5) =161a(6) =183a(7) =201a(8) =411a(9) =543a(10) =1003a(11) =1043a(12) =1387a(13) =1389a(14) =1527a(15) =1589a(16) =2509a(17) =2519a(18) =2559a(19) =2881a(20) =4143a(21) =4613a(22) =4821a(23) =5251a(24) =6821a(25) =7123a(26) =7671a(27) =7679a(28) =8373a(29) =9993

External references