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Prime numbers n such that x' = n has two solutions, where x' is the arithmetic derivative (A003415) of x.
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%I #6 Mar 30 2012 17:22:58

%S 31,61,71,101,103,131,199,211,241,269,359,401,421,433,439,571,619,641,

%T 661,719,727,739,751,761,811,1019,1051,1063,1193,1277,1279,1303,1307,

%U 1321,1451,1471,1499,1613,1619,1667,1697,1721,1723,1783,1879,1949

%N Prime numbers n such that x' = n has two solutions, where x' is the arithmetic derivative (A003415) of x.

%C The primes in A189555.

%Y Cf. A003415.

%K nonn

%O 1,1

%A _T. D. Noe_, Apr 24 2011