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

1,2

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

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 *)

Prog

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

Crossrefs

Cf. A016861, A107744, A107745, A107747.

Sequence in context: A367861 A214432 A110086 * A024899 A114518 A066940

Adjacent sequences: A107743 A107744 A107745 * A107747 A107748 A107749

Keyword

nonn

Author

Zak Seidov, May 23 2005

Extensions

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

Status

approved