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A331555
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Prime numbers p_k such that p_k == 1 (mod 10) and p_(k+1) == 3 (mod 10).
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6
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11, 41, 71, 101, 191, 211, 281, 311, 431, 461, 521, 641, 661, 821, 881, 1031, 1061, 1091, 1151, 1201, 1301, 1451, 1481, 1511, 1531, 1721, 1811, 1871, 1931, 1951, 2081, 2111, 2141, 2311, 2381, 2591, 2621, 2711, 2801, 3191, 3251, 3331, 3371, 3461, 3581, 3671, 3821, 3851, 3931
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OFFSET
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1,1
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LINKS
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MAPLE
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filter:= p -> isprime(p) and nextprime(p) mod 10 = 3:
select(filter, [seq(i, i=1..4000, 10)]); # Robert Israel, Feb 20 2020
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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] == 3 &] (* Amiram Eldar, Jan 20 2020 *)
Prime[#]&/@SequencePosition[Table[Which[Mod[n, 10]==1, 1, Mod[n, 10]==3, -1, True, 0], {n, Prime[Range[600]]}], {1, -1}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 10 2020 *)
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PROG
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(PARI) isok(p) = isprime(p) && ((p % 10)==1) && ((nextprime(p+1) % 10) == 3); \\ Michel Marcus, Jan 20 2020
(Magma) [p: p in PrimesUpTo(4500)| (p mod 10 eq 1) and (NextPrime(p) mod 10 eq 3)]; // Marius A. Burtea, Jan 20 2020
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CROSSREFS
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Cf. A030430 (1, any), A330366 (1, 1), this sequence (1, 3), A331324 (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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