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A242773
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The greater of twin primes p2 such that 2*p1 + p2 is a prime number (A174913) and also the lesser of other twin primes in A174913.
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2
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7, 11491, 32971, 33331, 33601, 42841, 58111, 93811, 96331, 114601, 180181, 273001, 309541, 334891, 401311, 540541, 633571, 717091, 784351, 820411, 870241, 879691, 907141, 948091, 989251, 991621, 994561, 1020961, 1028581, 1044751, 1185661, 1189651, 1245451, 1253911
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OFFSET
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1,1
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COMMENTS
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It seems that a(n) == 1 mod 10 for n > 1.
a(n) == 1 (mod 10) for n > 1 since if p2 == 3, 7 or 9 (mod 10) then 2*p1 + p2, p1, or 2*p1 + p2 + 2 is divisible by 5, respectively. - Amiram Eldar, Dec 31 2019
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LINKS
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FORMULA
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EXAMPLE
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MATHEMATICA
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Select[Range[10^6], And @@ PrimeQ[{#, # + 2, (p = 3*# + 2), p + 2, 3*p + 2}] &] + 2 (* Amiram Eldar, Dec 31 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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