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 A076532 #10 Oct 04 2019 08:48:29 %S A076532 2,90,425,490,605,630,726,735,750,816,2250,2695,3185,3234,3420,3822, %T A076532 4176,5096,5250,6591,7644,8470,9100,9425,10296,10780,11616,11638, %U A076532 12321,15750,16940,18096,22736,23276,25578,27360,27783,28500,31900,36400 %N A076532 Numbers n such that sopf(sigma(n)) = sigma(sopf(n)), where sopf(x) = sum of the distinct prime factors of x. %H A076532 Amiram Eldar, <a href="/A076532/b076532.txt">Table of n, a(n) for n = 1..10000</a> %e A076532 sopf(sigma(90)) = sopf(234) = 18; sigma(sopf(90)) = sigma(10) = 18, hence 90 is a term of the sequence. %t A076532 p[n_] := Apply[Plus, Transpose[FactorInteger[n]][[1]]]; Select[Range[2, 10^4], p[DivisorSigma[1, # ]] == DivisorSigma[1, p[ # ]] &] %o A076532 (PARI) isok(n) = (n>1) && sigma(sopf(n)) == sopf(sigma(n)); \\ _Michel Marcus_, Oct 04 2019 %Y A076532 Cf. A008472, A075565, A075784, A075846, A076525, A076527, A076531, A076533. %K A076532 nonn %O A076532 1,1 %A A076532 _Joseph L. Pe_, Oct 18 2002 %E A076532 Edited and extended by _Ray Chandler_, Feb 13 2005