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 A062823 #30 Jan 31 2025 04:21:53
%S A062823 1,3,7,11,13,14,15,19,22,23,25,28,29,31,35,39,41,43,44,46,47,50,53,55,
%T A062823 56,59,61,62,67,68,70,71,73,77,78,79,82,83,86,87,88,89,91,92,93,94,95,
%U A062823 97,99,103,107,109,110,111,112,113,115,117,118,119,122,124,127,129,131
%N A062823 Numbers k such that the number of divisors of k divides the number of divisors of the totient of k.
%H A062823 Amiram Eldar, <a href="/A062823/b062823.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1001 from Harry J. Smith)
%e A062823 For k = {3,11,29}, phi(k) = {2,10,28}, d(phi(k)) = {2,4,6}, d(k) = 2, quotient = {1,2,3}.
%t A062823 Select[Range@ 132, Mod @@ DivisorSigma[0, {EulerPhi@ #, #}] == 0 &] (* _Michael De Vlieger_, Jun 29 2018 *)
%o A062823 (PARI) select(m->frac(numdiv(eulerphi(m))/numdiv(m)) == 0, [1..500]) \\ _Harry J. Smith_, Aug 11 2009
%o A062823 (PARI) isok(k) = {my(f = factor(k)); !(numdiv(eulerphi(f)) % numdiv(f));} \\ _Amiram Eldar_, Jan 31 2025
%Y A062823 Cf. A000005, A000010, A062821.
%K A062823 nonn
%O A062823 1,2
%A A062823 _Labos Elemer_, Jul 20 2001
%E A062823 Incorrect formula deleted by _Jon E. Schoenfield_, Jul 02 2018
%E A062823 Offset corrected by _Amiram Eldar_, Jan 31 2025