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A245042
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Primes of the form (k^2+4)/5.
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2
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17, 73, 89, 193, 337, 521, 953, 1009, 1249, 1657, 2377, 2833, 3329, 3433, 4441, 4561, 5849, 6553, 7297, 8081, 8737, 9769, 11617, 12401, 12601, 13417, 15569, 16937, 17881, 18121, 20353, 21649, 27529, 28729, 29033, 30577, 33457, 35449, 36809, 46273, 49801
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OFFSET
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1,1
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COMMENTS
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Also equal to primes p such that 5*p-4 is a perfect square.
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LINKS
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MATHEMATICA
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PROG
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(Python)
import sympy
L = (k**2 + 4 for k in range(10**3))
[n//5 for n in L if n % 5 == 0 and sympy.ntheory.isprime(n//5)]
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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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