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Search: id:A093245
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| A093245 |
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a(n) is the lesser term of the smallest twin prime pair such that if P=(a(n)^2+n)^2+n, then P and P+2 are also twin primes. |
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+0
2
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| 3, 71, 0, 419, 71, 0, 5, 11, 0, 10271, 24977, 0, 29, 6869, 0, 3, 9011, 0, 881, 29, 0, 641, 17, 0, 41, 107, 0, 17, 179, 0, 5, 2801, 0, 10859, 11, 0, 59, 40637, 0, 461, 17957, 0, 431, 431, 0, 24977, 5, 0, 12611, 599, 0, 9431, 1091, 0, 107, 5867, 0, 3, 15731, 0, 5, 659, 0
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Note that either P or P+2 is composite whenever n is a multiple of 3, and in this case a(n)=0.
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EXAMPLE
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a(5) = 71: 71 and 73 are twin primes. (71^2+5)^2+5 = 25462121. 25462121 and 25462123 are also twin primes.
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MATHEMATICA
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f[n_] := Block[{k = 2}, If[ Mod[n, 3] != 0, While[ p = Prime[k]; q = (p^2 + n)^2 + n; !PrimeQ[p + 2] || !PrimeQ[q] || !PrimeQ[q + 2], k++ ]; p, 0]]; Table[ f[n], {n, 63}] (from Robert G. Wilson v Sep 02 2004)
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CROSSREFS
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Cf. A093189.
Sequence in context: A000282 A140048 A135951 this_sequence A108231 A130894 A106894
Adjacent sequences: A093242 A093243 A093244 this_sequence A093246 A093247 A093248
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KEYWORD
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nonn
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AUTHOR
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Ray G. Opao (1260(AT)email.com), May 11 2004
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EXTENSIONS
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Corrected and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 2 2004
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