This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A085556 #14 Apr 13 2024 19:27:25 %S A085556 12,13,15,17,20,21,24,26,28,29,30,31,34,36,38,39,42,43,45,47,50,51,54, %T A085556 56,58,59,62,63,65,67,70,71,74,76,78,79,82,83,85,87,92,93,95,97,1022, %U A085556 1023,1025,1027,1032,1033,1035,1037,1052,1053,1055,1057,1072,1073,1075 %N A085556 Numbers that have exactly as many prime digits as nonprime digits. %t A085556 Select[Range[1200],Count[IntegerDigits[#],_?PrimeQ]== IntegerLength[#]/2&] (* _Harvey P. Dale_, Jun 02 2011 *) %Y A085556 Cf. A085520. %K A085556 base,easy,nonn %O A085556 1,1 %A A085556 _Jason Earls_, Jul 04 2003