%N Primes which when concatenated with the previous prime form a new prime.
%F If isprime(p(n) & p(n-1)) then sequence.add(p(n))
%e a(2) = 53 because 53 concatenated with the preceding prime (47) yields 5347 which is also prime.
%Y Cf. A088784.
%A Chuck Seggelin (barkeep(AT)plasteredDragon.com), Oct 15 2003