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.

A071822 Numbers whose largest prime factor is of the form 4k+3.

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%I A071822 #10 May 04 2022 07:25:47
%S A071822 3,6,7,9,11,12,14,18,19,21,22,23,24,27,28,31,33,35,36,38,42,43,44,46,
%T A071822 47,48,49,54,55,56,57,59,62,63,66,67,69,70,71,72,76,77,79,81,83,84,86,
%U A071822 88,92,93,94,95,96,98,99,103,105,107,108,110,112,114,115,118,121,124
%N A071822 Numbers whose largest prime factor is of the form 4k+3.
%H A071822 Amiram Eldar, <a href="/A071822/b071822.txt">Table of n, a(n) for n = 1..10000</a>
%F A071822 Numbers k such that A006530(k) == 3 (mod 4).
%t A071822 Select[Range[125], Mod[FactorInteger[#][[-1,1]], 4] == 3 &] (* _Amiram Eldar_, May 04 2022 *)
%o A071822 (PARI) for(n=2,200,if((component(component(factor(n),1),omega(n))-3)%4==0,print1(n,",")))
%Y A071822 Cf. A004767, A006530, A071821.
%K A071822 easy,nonn
%O A071822 1,1
%A A071822 _Benoit Cloitre_, Jun 07 2002