A107746 Numbers k such that the least prime factor of 6*k+1 > the least prime factor of 6*k-1, A107744(k) > A107745(k).

1, 2, 3, 5, 6, 7, 10, 11, 12, 13, 16, 17, 18, 20, 21, 23, 25, 26, 27, 30, 31, 32, 33, 35, 36, 37, 38, 40, 41, 45, 46, 47, 48, 51, 52, 55, 56, 58, 61, 62, 63, 66, 68, 70, 71, 72, 73, 76, 77, 81, 83, 86, 87, 88, 90, 91, 95, 96, 97, 100, 101, 102, 103, 105, 106, 107, 110, 111

Offset: 1

Author

Zak Seidov, May 23 2005

Keywords

• nonn

Comments

Complement of A107747 in the positive integers.

Contains A016861. - Robert Israel, Oct 23 2015

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A016861, A107744, A107745, A107747.

Programs

Maple

lpf:= n -> min(numtheory:-factorset(n)):
select(n -> lpf(6*n+1) > lpf(6*n-1), [$1..1000]); # Robert Israel, Oct 23 2015

Mathematica

Select[Range@ 111, FactorInteger[6 # + 1][[1, 1]] > FactorInteger[6 # - 1][[1, 1]] &] (* Michael De Vlieger, Oct 23 2015 *)

PARI

isok(n) = vecmin(factor(6*n+1)[,1]) > vecmin(factor(6*n-1)[,1]); \\ Michel Marcus, Feb 04 2014

Extensions

Comments corrected and (at the suggestion of Michel Marcus) moved to Crossrefs by Jason Kimberley, Oct 23 2015