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Prime numbers containing an equal, nonzero number of odd nonprime digits and of even prime digits.
1

%I #12 Aug 11 2019 11:04:19

%S 29,127,239,241,251,269,271,281,293,421,521,821,829,1229,1237,1277,

%T 1283,1327,1423,1427,1523,1627,1723,1823,2017,2039,2069,2081,2089,

%U 2129,2137,2143,2153,2309,2339,2341,2351,2371,2381,2389,2393,2417,2441,2459,2531

%N Prime numbers containing an equal, nonzero number of odd nonprime digits and of even prime digits.

%C Even prime digit = 2. Odd nonprime digits are 1 or 9.

%H Harvey P. Dale, <a href="/A157145/b157145.txt">Table of n, a(n) for n = 1..1000</a>

%t onpdQ[n_]:=Module[{od=DigitCount[n,10,1]+DigitCount[n,10,9],ev= DigitCount[ n,10,2]},od==ev>0]; Select[Prime[Range[400]],onpdQ] (* _Harvey P. Dale_, Aug 11 2019 *)

%Y Cf. A000040.

%K nonn,base,less

%O 1,1

%A _Juri-Stepan Gerasimov_, Feb 24 2009

%E Definition corrected and terms 2069..2089 inserted by _R. J. Mathar_, May 15 2010