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A064905
Semiprimes p1*p2 such that p2>p1 and p2 mod p1 = 7.
1
319, 697, 767, 803, 1219, 1529, 1577, 1781, 1853, 2119, 2497, 2981, 3133, 3223, 3587, 3649, 3707, 3743, 3809, 3949, 4061, 4393, 4747, 5161, 5249, 5321, 5401, 5837, 5899, 5909, 5983, 5989, 6127, 6509, 6611, 6631, 6931, 7633, 7697, 8063, 8203, 8473, 8797, 8879
OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000 (corrected by Sean A. Irvine)
MATHEMATICA
m7Q[n_]:=Module[{f=Transpose[FactorInteger[n]][[1]]}, Length[f]==2 && Mod[ f[[2]], f[[1]]]==7]; Select[Range[10000], And[m7Q[#], SquareFreeQ[#]] &] (* Harvey P. Dale, May 02 2016; corrected by Michael De Vlieger, Jul 31 2023 *)
nn = 8900; m = 7; Union@ Flatten@ Table[p = Prime[i]; Table[q = Prime[j]; If[Mod[q, p] == m, p q, Nothing], {j, i + 1, PrimePi[nn/p]}], {i, PrimePi[nn]}] (* Michael De Vlieger, Jul 31 2023 *)
CROSSREFS
Cf. A001358 (p2 mod p1 = 0), A064899-A064911.
Sequence in context: A053020 A250660 A252410 * A293921 A121010 A110289
KEYWORD
nonn
AUTHOR
Patrick De Geest, Oct 13 2001
EXTENSIONS
Corrected and extended by Harvey P. Dale, May 02 2016
Original data restored, name clarified, and offset corrected by Sean A. Irvine, Jul 31 2023
STATUS
approved