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 A379923 #7 Jan 06 2025 10:55:16
%S A379923 1,5,18,22,25,29,197,1350,1360,1362,1368,1381,1391,1395,10200,75486,
%T A379923 75490,557768,557843,557853,557898,4121846,4122064,4122112,4122222,
%U A379923 30457732,30457773,30457835,30458040,30458133,30458138,30458140,30458335,225056911,225056919,225056925,225056989
%N A379923 Numbers m that divide the alternating sum Sum_{k=1..m} (-1)^k * A000005(k).
%C A379923 Numbers m such that m | A307704(m).
%C A379923 The corresponding quotients, A307704(m)/m, are -1, 0, 1, 1, 1, 1, 2, 3, 3, 3, ... (see the link for more values).
%C A379923 a(38) > 2*10^10, if it exists.
%H A379923 Amiram Eldar, <a href="/A379923/a379923.txt">Table of n, a(n), A307704(a(n))/a(n) for n = 1..37</a>.
%t A379923 With[{m = 10000}, Position[Accumulate[Table[(-1)^n * DivisorSigma[0, n], {n, 1, m}]]/Range[m], _?IntegerQ] // Flatten]
%o A379923 (PARI) list(lim) = my(s = 0); for(k = 1, lim, s += (-1)^k * numdiv(k); if(!(s % k), print1(k, ", ")));
%Y A379923 Cf. A000005, A307704.
%Y A379923 Similar sequences: A050226, A048290, A056550, A064605, A067929, A067931, A379922, A379924.
%K A379923 nonn
%O A379923 1,2
%A A379923 _Amiram Eldar_, Jan 06 2025