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A138111
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Prime numbers p1 such that p1*p2 - (p2 mod p1) is a prime, where p2 is the next prime after p1.
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5
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2, 3, 7, 19, 23, 43, 53, 79, 127, 211, 229, 233, 337, 397, 443, 463, 467, 499, 503, 601, 631, 661, 967, 991, 1009, 1129, 1153, 1213, 1237, 1279, 1297, 1381, 1399, 1423, 1447, 1453, 1471, 1511, 1597, 1621, 1699, 1723, 1783, 1831, 1879, 1993, 2029, 2297, 2437, 2543, 2647
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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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2 is prime, 3 is next prime, 2*3 - (3 mod 2) = 2*3 - 1 = 5 is prime.
3 is prime, 5 is next prime, 3*5 - (5 mod 3) = 3*5 - 2 = 13 is prime.
7 is prime, 11 is next prime, 7*11 - (11 mod 7) = 7*11 - 4 = 73 is prime.
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MATHEMATICA
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a={}; Do[p1=Prime[n]; p2=Prime[n+1]; e=p1*p2-Mod[p2, p1]; If[PrimeQ[e], AppendTo[a, p1]], {n, 10^2*2}]; a
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PROG
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(PARI) ok(p)={my(q=nextprime(p+1)); isprime(p) && isprime(p*q - (q%p))}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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