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 A329880 #9 Sep 12 2020 03:21:07 %S A329880 24,40,56,76,88,104,108,116,120,136,152,168,184,228,232,236,248,261, %T A329880 264,280,296,312,316,328,342,344,348,356,376,380,408,424,436,440,456, %U A329880 472,488,520,522,531,532,536,540,552,556,568,580,584,596,616,632,664,680 %N A329880 Numbers k such that the sums of unitary and nonunitary divisors of k have the same set of prime divisors. %C A329880 Numbers k such that rad(usigma(k)) = rad(nusigma(k)), where rad(k) is the squarefree kernel of k (A007947), usigma(k) is the sum of unitary divisors of k (A034448) and nusigma(k) = sigma(k) - usigma(k) is the sum of nonunitary divisors of k (A048146). %C A329880 Numbers k such that rad(usigma(k)) = rad(nusigma(k)) = rad(k) are 24, 3780, 26460, ... with no other term below 3*10^9. %H A329880 Amiram Eldar, <a href="/A329880/b329880.txt">Table of n, a(n) for n = 1..10000</a> %t A329880 rad[n_] := Times @@ (First@# & /@ FactorInteger@ n); usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); nusigma[n_] := DivisorSigma[1, n] - usigma[n]; Select[Range[700], rad[usigma[#]] == rad[nusigma[#]] &] %Y A329880 Cf. A007947, A034448, A048146, A329858, A329879. %K A329880 nonn %O A329880 1,1 %A A329880 _Amiram Eldar_, Nov 23 2019