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 A333742 #11 Aug 16 2024 12:20:24 %S A333742 4,6,7,180,208,427,1183,1330,1404,1480,1584,1651,1672,2013,2695,2715, %T A333742 3256,3439,5250,5668,5698,5950,5955,7600,12243,13392,13715,14768, %U A333742 22263,22878,23347,24804,26100,30500,32940,43648,45870,46205,52548,54481,59148,59780,62719 %N A333742 Numbers k such that lambda(k) = lambda(k+2), where lambda is the Carmichael lambda function (A002322). %H A333742 Amiram Eldar, <a href="/A333742/b333742.txt">Table of n, a(n) for n = 1..5000</a> %e A333742 4 is a term since lambda(4) = lambda(6) = 2. %t A333742 Select[Range[10^4], CarmichaelLambda[#] == CarmichaelLambda[# + 2] &] %t A333742 Position[Partition[CarmichaelLambda[Range[63000]],3,1],_?(#[[3]]==#[[1]]&),1,Heads->False]//Flatten (* _Harvey P. Dale_, Aug 16 2024 *) %Y A333742 Cf. A001494, A002322. %K A333742 nonn %O A333742 1,1 %A A333742 _Amiram Eldar_, Apr 03 2020