A114549 - OEIS

%I #12 Feb 10 2016 17:44:16

%S 2,23,29,41,47,83,89,101,103,107,109,127,149,163,167,181,211,233,239,

%T 251,257,271,277,293,307,347,349,367,383,389,419,431,433,439,457,479,

%U 491,503,509,521,523,541,547,563,569,587,613,617,619,631,653,659,673

%N Prime numbers p for which (sum of the digits of p) + (number of the digits of p) is a prime.

%H Harvey P. Dale, <a href="/A114549/b114549.txt">Table of n, a(n) for n = 1..1000</a>

%e 89 is in the sequence because (1) it is a prime number, (2) the sum of the digits is 8+9=17, the number of digits is 2 and (3) 17+2=19, which is a prime number.

%t Select[Prime[Range[150]],PrimeQ[Total[IntegerDigits[#]]+ IntegerLength[ #]]&] (* _Harvey P. Dale_, Jan 28 2015 *)

%o (PARI) isok(p) = isprime(p) && isprime(sumdigits(p) + #digits(p)); \\ _Michel Marcus_, Feb 26 2014

%K base,nonn

%O 1,1

%A Luc Stevens (lms022(AT)yahoo.com), Apr 20 2006

%E Corrected by _Harvey P. Dale_, Jan 28 2015