login
Primes p such that (number of prime digits of p) < (number of prime digits of prime(p)).
2

%I #20 Feb 19 2021 02:58:00

%S 11,19,31,41,59,61,67,71,101,103,107,109,131,137,139,149,151,181,191,

%T 199,211,241,269,281,307,311,331,349,367,389,401,409,419,439,449,457,

%U 461,463,467,479,491,499,503,509,521,569,587,599,601,613,619,641,643

%N Primes p such that (number of prime digits of p) < (number of prime digits of prime(p)).

%C Prime digits are 2, 3, 5, 7.

%H John Cerkan, <a href="/A155555/b155555.txt">Table of n, a(n) for n = 1..10000</a>

%o (PARI) dp(n)=d=digits(n);c=0;for(i=1,#d,if(isprime(d[i]),c+=1));c

%o forprime(p=1,500,if(dp(p)<dp(prime(p)),print1(p,", "))) \\ _Derek Orr_, Feb 28 2017

%Y Cf. A000040, A109066, A155552.

%K nonn,base,less

%O 1,1

%A _Juri-Stepan Gerasimov_, Jan 24 2009

%E Corrected (87 removed) by _R. J. Mathar_, May 15 2010