|
%I #14 Mar 11 2017 21:24:16
%S 2,5,17,19,23,31,37,43,71,163,179,199,263,269,347,379,389,443,467,487,
%T 499,569,601,641,643,647,683,691,709,769,821,829,857,859,919,941,947,
%U 953,967,997,1019,1021,1061,1093,1123,1153,1231,1249,1381,1409,1459
%N Primes which are the sum of the digital root of the first n primes for some n.
%H Harvey P. Dale, <a href="/A075544/b075544.txt">Table of n, a(n) for n = 1..1000</a>
%t s = 0; Do[s = s + Mod[ Prime[n], 9]; If[ PrimeQ[s], Print[s]], {n, 1, 350} ]
%t Select[Accumulate[Mod[Prime[Range[1000]],9]],PrimeQ] (* _Harvey P. Dale_, May 04 2012 *)
%o (PARI) sumdigits2(n)=local(c); while (n>9,c=0; while (n>0,c=c+n%10; n=n-n%10; n=n/10); n=c); n
%o c=0; forprime (p=2,1000,c=c+sumdigits2(p); if (isprime(c),print1(c,",")))
%Y Cf. A010888, A104247.
%K nonn,base
%O 1,1
%A _Jon Perry_, Oct 11 2002
%E Edited by _Robert G. Wilson v_, Oct 14 2002
%E Definition corrected by _M. F. Hasler_, Apr 04 2007
%E Corrected by _Harvey P. Dale_, May 04 2012
|
