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 A076533 #12 Aug 21 2024 22:49:38 %S A076533 1,3,14,35,42,70,105,119,209,210,238,248,297,357,412,418,477,594,595, %T A076533 616,627,714,744,954,1045,1142,1178,1190,1236,1240,1254,1328,1339, %U A076533 1463,1485,1672,1674,1703,1736,1785,1848,1863,2079,2090,2376,2385,2540,2728 %N A076533 Numbers n such that sum of the distinct prime factors of phi(n) = sum of the distinct prime factors of sigma(n). %H A076533 Charles R Greathouse IV, <a href="/A076533/b076533.txt">Table of n, a(n) for n = 1..10000</a> %e A076533 sopf(sigma(14)) = 5; sopf(phi(14)) = 5; hence 14 is a term of the sequence. %t A076533 p[n_] := Apply[Plus, Transpose[FactorInteger[n]][[1]]]; Select[Range[3, 10^4], p[DivisorSigma[1, # ]] == p[EulerPhi[ # ]] &] %t A076533 Select[Range[3000],Total[FactorInteger[DivisorSigma[1,#]][[All,1]]] == Total[ FactorInteger[EulerPhi[#]][[All,1]]]&] (* _Harvey P. Dale_, Sep 20 2016 *) %o A076533 (PARI) sopf(n)=my(f=factor(n)[,1]); sum(i=1,#f,f[i]) %o A076533 is(n)=sopf(sigma(n))==sopf(eulerphi(n)) \\ _Charles R Greathouse IV_, Mar 09 2014 %Y A076533 Cf. A008472, A075565, A075784, A075846, A076525, A076527, A076531, A076532. %K A076533 nonn %O A076533 1,2 %A A076533 _Joseph L. Pe_, Oct 18 2002 %E A076533 Edited by _Ray Chandler_, Feb 13 2005 %E A076533 a(1) inserted by _Charles R Greathouse IV_, Mar 09 2014