# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a286322 Showing 1-1 of 1 %I A286322 #15 May 12 2017 03:31:42 %S A286322 4,9,221,289,697,1819,2329,4369,4913,6439,18769,21331,35209,66049, %T A286322 128881,184783,197143,258121,281929,516961,739903,971203,1762249, %U A286322 1942663,2070721,2898703,2952673,3820819,4142881,5550943,5869681,8288641,16230481,16773619 %N A286322 Totient highly abundant numbers that are composite. %C A286322 Intersection of A002808 and A286267. %C A286322 Of the 65 terms below 10^9, only 2 have more than 2 prime factors: a(9) = 17^3 and a(36) = 257^3, and 11 are prime powers: a(1) = 2^2, a(2) = 3^2, a(4) = 17^2, a(9) = 17^3, a(11) = 137^2, a(14) = 257^2, a(15) = 359^2, a(20) = 719^2, a(25) = 1439^2, a(32) = 2879^2, and a(36) = 257^3. %H A286322 Amiram Eldar and Giovanni Resta, Table of n, a(n) for n = 1..93 (terms < 5*10^10, first 65 terms from Amiram Eldar) %t A286322 sumTot[n_] := Plus @@ FixedPointList[ EulerPhi@ # &, n] - 1; a={};smax=0;For[k=1,k<300000,k++;s=sumTot[k];If[s>smax,smax=s;If[!PrimeQ[k],a=AppendTo[a,k]]]];a %Y A286322 Cf. A002808, A286267. %K A286322 nonn %O A286322 1,1 %A A286322 _Amiram Eldar_, May 07 2017 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE