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Search: id:A108231
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| A108231 |
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a(n) = the first prime in the earliest sequence of 2n+1 consecutive primes whose average is prime. |
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+0
1
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| 3, 71, 7, 463, 31, 43, 5, 7, 499, 821, 109, 97, 271, 263, 179, 97, 181, 47, 233, 1931, 359, 227, 1787, 443, 29, 131, 1061, 229, 599, 1931, 7, 317, 53, 2207, 811, 11549, 2411, 2879, 5531, 937, 2371, 293, 21001, 659, 643, 1187, 2927, 4567, 131, 263, 8419, 349
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OFFSET
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1,1
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EXAMPLE
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71 is the first prime in the earliest sequence of 5 = 2 * 2 + 1 consecutive primes whose average is a prime, since (71 + 73 + 79 + 83 + 89)/5 = 79. Therefore a(2) = 71.
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MATHEMATICA
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f[n_] := Block[{k = 1}, While[ !PrimeQ[ Sum[ Prime[j], {j, k, 2n + k}]/(2n + 1)], k++ ]; Prime[k]]; Table[ f[n], {n, 52}] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 21 2005)
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CROSSREFS
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Sequence in context: A140048 A135951 A093245 this_sequence A130894 A106894 A094458
Adjacent sequences: A108228 A108229 A108230 this_sequence A108232 A108233 A108234
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KEYWORD
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nonn
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AUTHOR
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Joseph Pe (joseph_l_pe(AT)hotmail.com), Jun 16 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 21 2005
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