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A216816
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Primes congruent to 3 or 7 mod 20.
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6
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3, 7, 23, 43, 47, 67, 83, 103, 107, 127, 163, 167, 223, 227, 263, 283, 307, 347, 367, 383, 443, 463, 467, 487, 503, 523, 547, 563, 587, 607, 643, 647, 683, 727, 743, 787, 823, 827, 863, 883, 887, 907, 947, 967, 983, 1063, 1087, 1103, 1123, 1163, 1187, 1223, 1283, 1303, 1307, 1327, 1367, 1423, 1427, 1447, 1483, 1487
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OFFSET
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1,1
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COMMENTS
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This is a subsequence of A106865 but it is an important sequence in its own right.
This may actually be the same sequence as A122870, I did not check. If it is, I will merge the two entries.
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REFERENCES
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David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989; see p. 33.
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LINKS
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MATHEMATICA
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Select[Prime[Range[300]], MemberQ[{3, 7}, Mod[#, 20]]&] (* Vincenzo Librandi, Jan 06 2013 *)
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PROG
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(Magma) [p: p in PrimesUpTo(1500) | p mod 20 in [3, 7]]; // Vincenzo Librandi, Jan 06 2013
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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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