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A306627
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Primes of the form (p + prime(p))/2 with prime p.
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0
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43, 53, 79, 97, 199, 257, 347, 1103, 1187, 1303, 1367, 1753, 2029, 2351, 2593, 2647, 3181, 3253, 4663, 4787, 4903, 4919, 5573, 6091, 7079, 7331, 7369, 7457, 8101, 8527, 8543, 10159, 11549, 12647, 13151, 14699, 15031, 15559, 15679, 15881, 15889, 16661, 17099, 17881, 18251, 18959, 19219, 20399, 20431
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OFFSET
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1,1
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COMMENTS
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Indices k of p's are 8, 9, 11, 12, 19, 23, 28, 62, 64, 68, 71, 85, 95, 104, 114, 115, 131, 134, 175, 178, 181, 182, 200, 216, 240, 246, 247, 250, 266, 276, 277, 316, 346, 372, 382.
And some of k's themselves are prime: 11, 19, 23, 71, 131, 181, 277, 421, 541, 601, 673, 751, 881, 937. See link to Fernandez.
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LINKS
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EXAMPLE
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43 = (p + prime(p))/2 for p = 19 (prime),
53 = (p + prime(p))/2 for p = 23 (prime).
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PROG
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(PARI) lista(nn) = forprime(p=3, nn, k=(prime(p)+p)/2; if(isprime(k), print1(k, ", "))) \\ Jinyuan Wang, Mar 01 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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