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Numbers that have exactly as many prime digits as nonprime digits.
1

%I #14 Apr 13 2024 19:27:25

%S 12,13,15,17,20,21,24,26,28,29,30,31,34,36,38,39,42,43,45,47,50,51,54,

%T 56,58,59,62,63,65,67,70,71,74,76,78,79,82,83,85,87,92,93,95,97,1022,

%U 1023,1025,1027,1032,1033,1035,1037,1052,1053,1055,1057,1072,1073,1075

%N Numbers that have exactly as many prime digits as nonprime digits.

%t Select[Range[1200],Count[IntegerDigits[#],_?PrimeQ]== IntegerLength[#]/2&] (* _Harvey P. Dale_, Jun 02 2011 *)

%Y Cf. A085520.

%K base,easy,nonn

%O 1,1

%A _Jason Earls_, Jul 04 2003