A107746 - OEIS

%I #31 Nov 03 2024 02:04:01

%S 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,

%T 37,38,40,41,45,46,47,48,51,52,55,56,58,61,62,63,66,68,70,71,72,73,76,

%U 77,81,83,86,87,88,90,91,95,96,97,100,101,102,103,105,106,107,110,111

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

%C Complement of A107747 in the positive integers.

%C Contains A016861. - _Robert Israel_, Oct 23 2015

%H Amiram Eldar, <a href="/A107746/b107746.txt">Table of n, a(n) for n = 1..10000</a>

%p lpf:= n -> min(numtheory:-factorset(n)):

%p select(n -> lpf(6*n+1) > lpf(6*n-1), [$1..1000]); # _Robert Israel_, Oct 23 2015

%t Select[Range@ 111, FactorInteger[6 # + 1][[1, 1]] > FactorInteger[6 # - 1][[1, 1]] &] (* _Michael De Vlieger_, Oct 23 2015 *)

%o (PARI) isok(n) = vecmin(factor(6*n+1)[,1]) > vecmin(factor(6*n-1)[,1]); \\ _Michel Marcus_, Feb 04 2014

%Y Cf. A016861, A107744, A107745, A107747.

%K nonn

%O 1,2

%A _Zak Seidov_, May 23 2005

%E Comments corrected and (at the suggestion of _Michel Marcus_) moved to Crossrefs by _Jason Kimberley_, Oct 23 2015