%I A047949
%S A047949 0,0,1,2,1,4,5,4,7,8,7,10,9,8,13,14,13,12,17,16,19,20,19,22,21,20,25,
%T A047949 24,23,28,29,28,27,32,31,34,35,34,33,38,37,40,39,38,43,42,41,30,47,46,
%U A047949 49,50,49,52,53,52,55,54,53,48,51,50,45,62,61,64,63,62,67,68,67,66
%N A047949 a(2) = a(3) = 0; for n >= 4, a(n) = largest m such that n-m and n+m are 
               both primes, or -1 if no such m exists.
%H A047949 T. D. Noe, <a href="b047949.txt">Table of n, a(n) for n=2..10000</a>
%e A047949 49-30=19 and 49+30=79 are primes, so a(49)=30.
%Y A047949 Cf. A047160.
%Y A047949 Sequence in context: A165050 A165042 A165046 this_sequence A075423 A144774 
               A074720
%Y A047949 Adjacent sequences: A047946 A047947 A047948 this_sequence A047950 A047951 
               A047952
%K A047949 easy,nice,nonn
%O A047949 2,4
%A A047949 Lior Manor (lior.manor(AT)gmail.com)
%E A047949 Corrected by Harvey P. Dale (hpd1(AT)is2.nyu.edu), Dec 21 2000