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 A387055 #8 Aug 17 2025 11:17:52
%S A387055 1,2,24,36,40,56,60,84,88,104,132,136,152,156,184,204,225,228,232,248,
%T A387055 276,296,328,344,348,372,376,424,441,444,450,472,488,492,516,536,564,
%U A387055 568,584,600,632,636,664,708,712,732,776,804,808,824,852,856,872,876,882,904,948,996
%N A387055 Numbers that are unitarily divisible by their number of divisors.
%C A387055 Refactorable numbers (A033950) k whose number of divisors is a unitary divisor of k.
%C A387055 This sequence is infinite. For example, if p is an odd prime, then 8*p is a term.
%H A387055 Amiram Eldar, <a href="/A387055/b387055.txt">Table of n, a(n) for n = 1..10000</a>
%t A387055 q[k_] := Module[{d = DivisorSigma[0, k]}, Divisible[k, d] && CoprimeQ[d, k/d]]; Select[Range[1000], q]
%o A387055 (PARI) isok(k) = {my(d = numdiv(k)); !(k % d) && gcd(d, k/d) == 1;}
%Y A387055 Subsequence of A033950.
%Y A387055 Cf. A000005, A023534, A048166, A077610.
%K A387055 nonn,easy
%O A387055 1,2
%A A387055 _Amiram Eldar_, Aug 15 2025