a(n) is the first prime p such that the concatenations of n consecutive primes, starting with p, in both forward and backward directions, are prime.

A384958

a(n) is the first prime p such that the concatenations of n consecutive primes, starting with p, in both forward and backward directions, are prime.

Terms

    a(0) =2a(1) =199a(2) =313a(3) =139a(4) =67a(5) =113a(6) =163a(7) =1583a(8) =23789a(9) =941a(10) =131a(11) =5351a(12) =26801a(13) =2693a(14) =4073a(15) =15859a(16) =4919a(17) =23209a(18) =176053a(19) =86783a(20) =29717a(21) =20849a(22) =151289a(23) =50111a(24) =51971a(25) =23689a(26) =11807a(27) =180337a(28) =563a(29) =25153

External references