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 A173941 #15 Jul 17 2019 14:37:58 %S A173941 1,2,4,6,8,12,24,100,168,180,264,300,468,552,684,1100,1128,1260,1416, %T A173941 1848,1992,2340,2568,3276,3300,3600,3864,4008,4296,4788,4920,5208, %U A173941 5448,6072,6312,7056,7224,7896,8184,8328,8616,9192,9912 %N A173941 Numbers k such that tau(lambda(k)) = lambda(tau(k)). %C A173941 Previous name: tau(lambda(n)) = lambda(tau(n)) for the sequential application of the number of divisors of n and Carmichael lambda function. %C A173941 Numbers k such that A000005(A002322(k)) = A002322(A000005(k)). %H A173941 Amiram Eldar, <a href="/A173941/b173941.txt">Table of n, a(n) for n = 1..10000</a> %p A173941 with(numtheory): for n from 1 to 10000 do:if tau(lambda(n))=lambda(tau(n))then %p A173941 printf(`%d, `,n):else fi:od: %t A173941 Cases[Range[1000], k_ /; DivisorSigma[0,CarmichaelLambda[k]] == CarmichaelLambda[DivisorSigma[0,k]]] %o A173941 (PARI) lambda(n) = lcm(znstar(n)[2]); \\ A002322 %o A173941 isok(k) = numdiv(lambda(k)) == lambda(numdiv(k)); \\ _Michel Marcus_, Jul 17 2019 %Y A173941 Cf. A000005, A002322, A123101. %K A173941 nonn %O A173941 1,2 %A A173941 _Michel Lagneau_, Nov 26 2010 %E A173941 Name edited by _Michel Marcus_, Mar 18 2016