A195602 Primes written with prime number of Roman numerals.
2, 3, 7, 11, 19, 23, 41, 43, 47, 59, 61, 67, 79, 83, 97, 101, 109, 113, 131, 137, 149, 151, 157, 173, 199, 223, 227, 239, 241, 263, 281, 293, 311, 313, 317, 331, 349, 353, 401, 419, 421, 439, 443, 461, 463, 467, 479, 491, 509, 557, 569, 571, 577, 599, 601, 607, 619, 641, 643, 647
Offset: 1
Programs
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Mathematica
Select[Prime[Range[200]],PrimeQ[Length[Characters[IntegerString[#, "Roman"]]]]&] (* Harvey P. Dale, Mar 19 2013 *)
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PARI
Roman(n)=my(s);while(n,s+=[0,1,2,3,2,1,2,3,4,2][n%10+1];n\=10);s forprime(p=2,3999,if(isprime(Roman(p)),print1(p", "))) \\ Charles R Greathouse IV, Oct 06 2011