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A139460 a(n) = m such that 2*prime(n+m+1) + (product of n successive odd primes) is prime. 4


%S 1,1,1,1,2,3,3,1,1,2,1,1,9,2,7,21,7,25,4,3,18,7,4,7,11,5,1,1,61,5,20,

%T 6,22,16,11,17,1,70,6,5,5,22,9,52,108,16,1,32,42,15,5,66,6,8,3,38,17,

%U 4,23,93,8,16,6,1,39,7,9,10,21,57,40,2,15,39,16,7,5,13,138,95,58,8,47,11,39

%N a(n) = m such that 2*prime(n+m+1) + (product of n successive odd primes) is prime.

%C Or, a(n) = m such that primorial(n+1)/2+2*prime(n+m+1) is prime.

%C For positions of 1's in this sequence see A139461

%t k = 1; a = {}; Do[k = k*Prime[n]; m = 1; While[ ! PrimeQ[k + 2*Prime[n + m]], m++ ]; Print[m]; AppendTo[a, m], {n, 2, 200}]; a (*Artur Jasinski*)

%Y Cf. A067026, A067027, A139439, A139440, A139441, A139442, A139443, A139444, A139445, A139446, A139447, A139448, A139449, A139450, A139451, A139452, A139453, A139454, A139455, A139456, A139457, A103514, A139460, A139461, A139462, A139463.

%K nonn

%O 1,5

%A _Artur Jasinski_, Apr 22 2008; definition corrected May 09 2008

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Last modified December 16 14:52 EST 2018. Contains 318167 sequences. (Running on oeis4.)