A064905 Semiprimes p1*p2 such that p2>p1 and p2 mod p1 = 7.

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

Adjacent sequences: A064902 A064903 A064904 * A064906 A064907 A064908

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