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 A309272 #25 Oct 25 2019 08:57:23
%S A309272 1,2,5,15,31,40,66,81,315,966,1398,1768,30166,32335,98734,388033,
%T A309272 591597,1375056,14966304,15160528,50793208,51302236,99253376,
%U A309272 110994356,230465053,402340268,497982399,2027319577,2879855394,18450762682,29922126368,31711273834,40583934786
%N A309272 Numbers m such that m divides A173290(m) = Sum_{k=1..m} psi(k), where psi is the Dedekind psi function (A001615).
%C A309272 The corresponding quotients are 1, 2, 4, 12, 24, 31, 51, 62, 240, 735, 1063, 1344, 22924, 24572, 75029, 294870, 449560, 1044918, 11373028, 11520620, 38598210, 38985025, 75423522, 84345597, 175132440, 305741942, 378421246, 1540578144, 2188427680, 14020898356, 22738089456, 24097678498, 30840092321, ...
%e A309272 2 is in the sequence since psi(1) + psi(2) = 1 + 3 = 4 is divisible by 2.
%e A309272 5 is in the sequence since psi(1) + psi(2) + ... + psi(5) = 1 + 3 + 4 + 6 + 6 = 20 is divisible by 5.
%t A309272 psi[1] = 1; psi[n_] := n * Times @@ (1 + 1/Transpose[FactorInteger[n]][[1]]); seq = {}; s = 0; Do[s += psi[n]; If[Divisible[s, n], AppendTo[seq, n]], {n, 1, 10^4}]; seq
%Y A309272 Cf. A001615, A173290.
%Y A309272 Cf. A045345, A048290, A050226, A056550, A063971, A064605, A064606, A064607, A064610, A064611, A064612, A306950, A307043, A307161, A326488.
%K A309272 nonn
%O A309272 1,2
%A A309272 _Amiram Eldar_, Oct 23 2019
%E A309272 a(31)-a(33) from _Giovanni Resta_, Oct 24 2019