%I #14 Nov 28 2014 22:55:29
%S 6,61,613,6131,613141,61314119,6131411917,61314119171,6131411917181,
%T 613141191718127,61314119171812789,613141191718127893,
%U 61314119171812789379,6131411917181278937929,61314119171812789379291,61314119171812789379291111
%N Start with 6; thereafter, primes obtained by concatenating to the end of previous term the next smallest number that will produce a prime.
%C a(n+1) is the next smallest prime beginning with a(n). Initial term is 6. After a(1), these are the primes arising in A069608.
%e a(1) = 6 by definition.
%e a(2) is the next smallest prime beginning with 6, so a(2) = 61.
%e a(3) is the next smallest prime beginning with 61, so a(3) = 613.
%o (Python)
%o import sympy
%o from sympy import isprime
%o def b(x):
%o ..num = str(x)
%o ..n = 1
%o ..while n < 10**3:
%o ....new_num = str(x) + str(n)
%o ....if isprime(int(new_num)):
%o ......print(int(new_num))
%o ......x = new_num
%o ......n = 1
%o ....else:
%o ......n += 1
%o b(6)
%Y Cf. A069608, A048553, A110773.
%K nonn,base
%O 1,1
%A _Derek Orr_, Jan 29 2014
