Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #5 Dec 05 2013 19:55:21
%S 0,0,0,0,1,0,1,2,1,1,1,2,2,2,1,3,3,3,2,3,1,3,3,5,2,4,2,4,3,4,3,4,4,3,
%T 2,6,4,5,2,6,4,6,3,6,4,5,5,7,4,6,4,5,4,8,3,5,4,7,5,9,3,7,5,8,5,7,3,8,
%U 4,8,5,10,6,7,5,8,4,9,6,9,7,8,4,10,5,7,6,8,7,12,5,8,8,8,5,12,6,10,5,10,5
%N Number of primes p such that n divided by p leaves a prime remainder.
%C Is there any n > 6 such that a(n) =0 ?
%e a(17) = 3: there are 3 primes viz. 3, 5 and 7 which leave prime remainders on dividing 17.
%t Table[Count[PrimeQ[Table[Mod[w, Prime[j]], {j, 1, PrimePi[w]}]], True], {w, 1, 256}]
%Y Cf. A072531.
%K nonn
%O 1,8
%A _Amarnath Murthy_, Aug 01 2002
%E More terms from _Labos Elemer_, Aug 02 2002