Search: id:A068066
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%I A068066
%S A068066 2,2,5,2,5,2,17,83,3,3,5,2,29,2,3,11,3,3,11,23,7,5,7,11,5,3,7,3,13,3,
%T A068066 13,5,7,17,5,3,5,73,13,5,7,5,7,5,7,29,7,53,11,29,17,31,3,23,3,47,97,5,
%U A068066 29,2,3,37,13,2,3,17,19,5,19,71,3,47,5,19,3,59,23,89,7,19,11,37,53,3
%N A068066 The sum or half the sum of n consecutive primes starting at a(n) is prime.
%C A068066 This eliminates the impossibles out of A007610 and the 'or' in the title 
               is the exclusive or.
%e A068066 a(3) = 5 because 5+7+11 = prime 23 and a(10) = 3 because 3+5+7+11+13+17+19+23+29+31 
               = 158 and half that or 79 is a prime.
%t A068066 Do[k = n; a = Table[Prime[i], {i, 1, n} ]; While[ !PrimeQ[Plus @@ a] 
               && !PrimeQ[Plus @@ a/2], k++; a = Drop[a, 1]; a = Append[a, Prime[k]]]; 
               Print[a[[1]]], {n, 1, 100} ]
%Y A068066 Cf. A007610.
%Y A068066 Sequence in context: A039931 A128645 A007610 this_sequence A101910 A162784 
               A093660
%Y A068066 Adjacent sequences: A068063 A068064 A068065 this_sequence A068067 A068068 
               A068069
%K A068066 nonn
%O A068066 1,1
%A A068066 Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 16 2002

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