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 A064610 #17 Jun 04 2021 03:15:37 %S A064610 1,35,37,1015,27417,27421,27449,27453,19774739,530743781,530743799, %T A064610 530743807,530743813 %N A064610 Places k where A064608(k) (partial sums of unitary tau) is divisible by k. %C A064610 The corresponding quotients are 1, 3, 3, 5, 7, 7, 7, 7, 11, 13, 13, 13, 13, ... %C A064610 a(14) > 7.5*10^10, if it exists. - _Amiram Eldar_, Jun 04 2021 %F A064610 {n: A064608(n) == 0 (mod n)}. %e A064610 For n = 37, the sum A064608(37) = 1+2+2+2+2+4+2+...+4+4+4+2 = 111 = 3*37, so 37 is in the sequence. %t A064610 s[1] = 1; s[n_] := s[n] = s[n - 1] + 2^PrimeNu[n]; Select[Range[30000], Divisible[s[#], #] &] (* _Amiram Eldar_, Jun 04 2021 *) %Y A064610 Cf. A064608. %Y A064610 Analogous "integer-mean" sequences for various arithmetical functions are A050226, A056650, A064605, A064606, A064607, A048290, A063986, A063971, A064911, A062982, A045345. %K A064610 nonn,more %O A064610 1,2 %A A064610 _Labos Elemer_, Sep 24 2001 %E A064610 a(10)-a(13) from _Donovan Johnson_, Jul 20 2012