A029556 Quasi-Carmichael numbers to base 7: squarefree composites n such that (n,2*3*5) = 1 and prime p|n ==> p-7|n-7.

187, 247, 4807, 12331, 21307, 32227, 50167, 61087, 62647, 82087, 89947, 101959, 113839, 118327, 127303, 137287, 140767, 141457, 168199, 187207, 193591, 214819, 234247, 235807, 259207, 283943, 306907, 358423, 369799, 396727, 422719, 424057

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Comments

If multiples of 2, 3 and 5 are not excluded, then terms like 15, 55, 715, 759, 1495,... belong to the sequence. - Giovanni Resta, May 21 2013

Links

• Giovanni Resta, Table of n, a(n) for n = 1..8274 (terms < 10^12)
• Index entries for sequences related to Carmichael numbers.

Programs

Mathematica

qcm[n_, d_] := Block[{p, e}, {p, e} = Transpose@FactorInteger@n; Length[p] > 1 && Max[e] == 1 && d < Min[p] && And @@ IntegerQ /@ ((n - d)/(p - d))]; Select[Range[10^6], qcm[#, 7] &] (* Giovanni Resta, May 21 2013 *)