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A047977
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Let (p1,p2), (p3,p4) be pairs of twin primes with p1*p2=p3+p4-1; sequence gives values of p2.
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2
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7, 13, 43, 73, 601, 643, 883, 2131, 2383, 2689, 3559, 3583, 4549, 6133, 7549, 8011, 9043, 13399, 13933, 15973, 17599, 19141, 21493, 26251, 26263, 34513, 38671, 39229, 39343, 48313, 49741, 52543, 53089, 53593, 55051, 55663, 56101
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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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E.g. 5*7=17+19-1,11*13=71+73-1.
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PROG
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(PARI) list(lim)=my(v=List(), p=3, r); forprime(q=5, lim, if(q-p==2 && isprime(r=p*q\2) && isprime(r+2), listput(v, q)); p=q); Vec(v) \\ Charles R Greathouse IV, Sep 29 2015
(PARI) is(n)=isprime(n) && isprime(n-2) && isprime(n*(n-2)\2) && isprime(n*(n-2)\2+2) \\ Charles R Greathouse IV, Sep 29 2015
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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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