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A049494
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a(n) and a(n)+4^k are primes at least for k=1,2,3,4.
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3
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7, 37, 163, 757, 967, 1303, 2293, 2377, 8677, 8803, 9157, 9277, 14827, 15667, 16417, 20113, 27763, 29863, 41953, 53593, 56527, 56893, 61027, 67153, 69763, 74827, 79333, 83203, 90007, 95467, 111577, 129277, 135193, 137383, 142543, 151783
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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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7,7+4=11,7+16=23,7+64=71,7+256=263 are all primes: it is the smallest such quintet.
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MATHEMATICA
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Select[Prime[Range[15000]], AllTrue[#+{4, 16, 64, 256}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jan 22 2018 *)
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PROG
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(PARI) isok(n) = isprime(n) && isprime(n+4) && isprime(n+4^2) && isprime(n+4^3) && isprime(n+4^4); \\ Michel Marcus, Dec 31 2013
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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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