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A165280
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If p and q are twin primes then pq + 1 is always divisible by 3, except for (p,q)=(3,5). Sequence gives values of (pq + 1)/3.
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1
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12, 48, 108, 300, 588, 1200, 1728, 3468, 3888, 6348, 7500, 10800, 12288, 13068, 17328, 19200, 24300, 26508, 32448, 40368, 58800, 62208, 71148, 90828, 108300, 120000, 127308, 137388, 145200, 218700, 225228, 228528, 245388, 259308, 346800
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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p = Rest@ Select[ Prime@ Range@ 175, PrimeQ[ # + 2] & ]; (p (p + 2) + 1)/3 (* Robert G. Wilson v, Sep 13 2009 *)
(Times@@#+1)/3&/@Select[Partition[Prime[Range[3, 200]], 2, 1], #[[2]]-#[[1]] == 2&] (* Harvey P. Dale, Aug 28 2022 *)
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PROG
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(Magma) [(p+1)^2 div 3: p in PrimesInInterval(5, 1100) |IsPrime(p+2)]; // Marius A. Burtea, Jan 02 2020
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Tanin (Mirza Sabbir Hossain Beg) (mirzasabbirhossainbeg(AT)yahoo.com), Sep 13 2009
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EXTENSIONS
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STATUS
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approved
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