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Largest digit of n concatenated with smallest digit of n is prime.
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%I #11 Oct 14 2019 00:08:33

%S 1,11,13,14,16,17,31,34,35,37,38,41,43,53,61,71,73,79,83,97,111,113,

%T 114,116,117,123,124,126,127,131,132,133,134,136,137,141,142,143,144,

%U 146,147,156,157,161,162,163,164,165,166,167,171,172,173,174,175,176,177

%N Largest digit of n concatenated with smallest digit of n is prime.

%e a(4)=14 because 41 is prime. a(8000)=47712 because 71 is prime.

%t Select[Range[2,200],PrimeQ[FromDigits[{Max[IntegerDigits[#]],Min[ IntegerDigits[#]]}]]&] (* _Harvey P. Dale_, Mar 29 2015 *)

%Y Cf. A054054, A054055.

%K base,easy,nonn

%O 1,2

%A _Jason Earls_, Jun 25 2003

%E Missing a(1)=1 inserted by _Sean A. Irvine_, Oct 13 2019