cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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).

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%I A107746 #31 Nov 03 2024 02:04:01
%S A107746 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 A107746 37,38,40,41,45,46,47,48,51,52,55,56,58,61,62,63,66,68,70,71,72,73,76,
%U A107746 77,81,83,86,87,88,90,91,95,96,97,100,101,102,103,105,106,107,110,111
%N 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).
%C A107746 Complement of A107747 in the positive integers.
%C A107746 Contains A016861. - _Robert Israel_, Oct 23 2015
%H A107746 Amiram Eldar, <a href="/A107746/b107746.txt">Table of n, a(n) for n = 1..10000</a>
%p A107746 lpf:= n -> min(numtheory:-factorset(n)):
%p A107746 select(n -> lpf(6*n+1) > lpf(6*n-1), [$1..1000]); # _Robert Israel_, Oct 23 2015
%t A107746 Select[Range@ 111, FactorInteger[6 # + 1][[1, 1]] > FactorInteger[6 # - 1][[1, 1]] &] (* _Michael De Vlieger_, Oct 23 2015 *)
%o A107746 (PARI) isok(n) = vecmin(factor(6*n+1)[,1]) > vecmin(factor(6*n-1)[,1]); \\ _Michel Marcus_, Feb 04 2014
%Y A107746 Cf. A016861, A107744, A107745, A107747.
%K A107746 nonn
%O A107746 1,2
%A A107746 _Zak Seidov_, May 23 2005
%E A107746 Comments corrected and (at the suggestion of _Michel Marcus_) moved to Crossrefs by _Jason Kimberley_, Oct 23 2015