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A141881
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Primes congruent to 1 mod 20.
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19
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41, 61, 101, 181, 241, 281, 401, 421, 461, 521, 541, 601, 641, 661, 701, 761, 821, 881, 941, 1021, 1061, 1181, 1201, 1301, 1321, 1361, 1381, 1481, 1601, 1621, 1721, 1741, 1801, 1861, 1901, 2081, 2141, 2161, 2221, 2281, 2341, 2381, 2441, 2521, 2621, 2741, 2801
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OFFSET
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1,1
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COMMENTS
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Such a prime is representable by either both or neither of the quadratic forms x^2 + 20 y^2 and x^2 + 100 y^2. See the Brink link. - Robert Israel, Jun 11 2014
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LINKS
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MAPLE
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select(isprime, [seq(20*i+1, i=1..1000)]); # Robert Israel, Jun 11 2014
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MATHEMATICA
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PROG
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(Magma) [p: p in PrimesUpTo(3000) | p mod 20 eq 1 ]; // Vincenzo Librandi, Aug 15 2012
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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