%I #7 Dec 15 2017 17:34:48
%S 11,13,17,19,20,23,29,30,31,32,37,47,50,59,67,70,71,73,74,76,79,89,91,
%T 92,95,97,98,102,103,105,107,111,113,117,119,120,123,127,129,130,131,
%U 132,133,137,139,147,149,150,157,159,167,169,170,171,172,173,174,175
%N Smallest digit of n concatenated with largest digit of n is prime.
%e a(5)=20 because 2 is prime. a(1300)=3295 because 29 is prime.
%Y Cf. A054054, A054055.
%K base,nonn
%O 1,1
%A _Jason Earls_, Jun 25 2003