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.
%I A284671 #10 Jun 26 2019 10:59:28 %S A284671 1729,41041,75361,172081,449065,656601,670033,1050985,2433601,2704801, %T A284671 3664585,4903921,6840001,7995169,8355841,8719921,9582145,9613297, %U A284671 9890881,10402561,11205601,12945745,13992265,15888313,16778881,17586361,17812081,19683001,20964961 %N A284671 Numbers n > 2 such that A258409(n)*A002322(n) divides n-1. %C A284671 A proper subset of the Carmichael numbers A002997. %C A284671 If n is in the sequence, then n-1 is not squarefree. %C A284671 Problem: are there infinitely many such numbers? %H A284671 Amiram Eldar, <a href="/A284671/b284671.txt">Table of n, a(n) for n = 1..10000</a> %t A284671 Select[Range[3, 10^6], Divisible[#-1, CarmichaelLambda[#] * GCD @@ (Divisors[#] - 1)] &] (* _Amiram Eldar_, Jun 26 2019 *) %Y A284671 Cf. A002322, A002997, A258409. %K A284671 nonn %O A284671 1,1 %A A284671 _Thomas Ordowski_ and _Altug Alkan_, Apr 01 2017