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A138303
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Numbers n such that n*(n+1)-1 and n*(n+1)+1 are twin primes and n*(n+3)-1 and n*(n+3)+1 are also twin primes.
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3
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3, 15, 495, 624, 1308, 1365, 1494, 1659, 1848, 6363, 8064, 12780, 13908, 14013, 16530, 18018, 18654, 28575, 30885, 31020, 38130, 43674, 48735, 50379, 57198, 60915, 61059, 62943, 75768, 76359, 76569, 80949, 81075, 83028, 84045, 86085, 88185, 104664, 105588
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OFFSET
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1,1
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LINKS
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EXAMPLE
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3*4=12: 11 and 13 are twin primes; 3*6=18 and 17 and 19 are also twin primes.
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PROG
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(PARI) isok(n) = isprime(n*(n+1)-1) && isprime(n*(n+1)+1) && isprime(n*(n+3)-1) && isprime(n*(n+3)+1); \\ Michel Marcus, Sep 23 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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