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A331324
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Prime numbers p_k such that p_k == 1 (mod 10) and p_(k+1) == 7 (mod 10).
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6
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31, 61, 131, 151, 251, 271, 331, 541, 571, 601, 751, 941, 971, 991, 1181, 1231, 1291, 1321, 1361, 1601, 1621, 1741, 1831, 1861, 1901, 2011, 2131, 2221, 2251, 2281, 2341, 2351, 2371, 2411, 2441, 2551, 2671, 2791, 2851, 3061, 3121, 3181, 3301, 3391, 3511, 3541, 3631, 3691, 3761, 3911
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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First @ Transpose @ Select[Partition[Select[Range[4500], PrimeQ], 2, 1], Mod[First[#], 10] == 1 && Mod[Last[#], 10] == 7 &] (* Amiram Eldar, Jan 20 2020 *)
Prime[#]&/@SequencePosition[Mod[Prime[Range[600]], 10], {1, 7}][[All, 1]] (* Harvey P. Dale, Oct 17 2022 *)
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PROG
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(Magma) [p: p in PrimesUpTo(4400)| (p mod 10 eq 1) and (NextPrime(p) mod 10 eq 7)]; // Marius A. Burtea, Jan 20 2020
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CROSSREFS
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Cf. A030430 (1, any), A330366 (1, 1), A331555 (1, 3), this sequence (1, 7), A030431 (3, any), A030432 (7, any), A030433 (9, any) [where (a, b) means p_k == a (mod 10) and p_(k+1) == b (mod 10)].
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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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