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 A374198 #16 Apr 17 2025 08:08:37
%S A374198 1,6,12,18,24,28,30,36,42,48,54,56,60,66,72,78,84,90,96,102,108,112,
%T A374198 114,120,126,132,138,140,144,150,156,162,168,174,180,186,192,196,198,
%U A374198 204,210,216,222,224,228,234,240,246,252,258,264,270,276,280,282,288,294,300,306,308,312,318,324,330,336,342,348,354,360
%N A374198 After initial 1, numbers k such that at least one of their divisors is a multiply-perfect number (A007691) larger than one.
%C A374198 A multiplicative semigroup: if m and n are in the sequence, then so is m*n.
%C A374198 The asymptotic density of this sequence is Sum_{s subset of A007691 \ {1}} (-1)^(card(s)+1)/LCM(s) = 0.1916963... . - _Amiram Eldar_, Apr 16 2025
%H A374198 Antti Karttunen, <a href="/A374198/b374198.txt">Table of n, a(n) for n = 1..20001</a>
%t A374198 q[n_] := n == 1 || AnyTrue[Rest[Divisors[n]], IntegerQ[DivisorSigma[-1, #]] &]; Select[Range[360], q] (* _Amiram Eldar_, Apr 16 2025 *)
%o A374198 (PARI) isA374198 = A374197;
%Y A374198 Indices of 1's in A374196.
%Y A374198 Cf. A007691, A097603 (essentially the same), A374197 (characteristic function).
%K A374198 nonn
%O A374198 1,2
%A A374198 _Antti Karttunen_, Jul 07 2024