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 A028442 #60 Feb 16 2025 08:32:35
%S A028442 2,39,40,58,65,93,101,145,149,150,159,160,163,164,166,214,231,232,235,
%T A028442 236,238,254,329,331,332,333,353,355,356,358,362,363,364,366,393,401,
%U A028442 403,404,405,407,408,413,414,419,420,422,423,424,425,427
%N A028442 Numbers k such that Mertens's function M(k) (A002321) is zero.
%H A028442 Seiichi Manyama, <a href="/A028442/b028442.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..5361 from T. D. Noe)
%H A028442 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MertensFunction.html">Mertens Function</a>.
%t A028442 Select[Range[500], Plus@@MoebiusMu[Range[#]] == 0 &] (* _Alonso del Arte_, Jul 06 2004 *)
%t A028442 seq[kmax_] := Position[Accumulate[MoebiusMu[Range[kmax]]], 0] // Flatten; seq[500] (* _Amiram Eldar_, Jun 09 2024 *)
%o A028442 (Perl) use ntheory ":all"; for (moebius(1,1e7)) { ++$i; say $i unless $M+=$_; } # _Dana Jacobsen_, May 22 2015
%o A028442 (PARI) isok(n) = sum(k=1, n, moebius(k)) == 0; \\ _Michel Marcus_, Nov 20 2017
%o A028442 (PARI) lista(kmax) = {my(s = 0); for(k = 1, kmax, s += moebius(k); if(s == 0, print1(k, ", ")));} \\ _Amiram Eldar_, Jun 09 2024
%o A028442 (Magma) M := func<i | &+[MoebiusMu(k): k in [1..i]]>; [n: n in [1..500] | M(n) eq 0]; // _Bruno Berselli_, Jul 12 2021
%Y A028442 Cf. A002321, A118684, A171096.
%K A028442 nonn
%O A028442 1,1
%A A028442 _Eric W. Weisstein_