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 A045835 #15 Aug 09 2024 01:56:40 %S A045835 1,4,9,14,18,21,25,26,33,38,42,46,49,50,57,62,69,74,78,85,92,93,94, %T A045835 106,110,121,129,130,133,134,138,140,145,154,164,166,169,177,178,189, %U A045835 204,205,213,217,218,222,225,226,230,236,237,249,253,254,262,265,266,278 %N A045835 Numbers n such that sopfr(Omega(n)) = Omega(sopfr(n)), where Omega(m) is the number and sopfr(m) is the sum of prime factors of m, with repetition respectively. %C A045835 A001414(A001222(a(n))) = A001222(A001414(a(n))); %C A045835 squares of primes (A001248) are a subsequence. %e A045835 n=189=3*3*3*7: Omega(sopfr(189))=Omega(3+3+3+7)=Omega(16)=4, sopfr(Omega(189))=sopfr(4)=2+2=4, therefore 189 is a term. %t A045835 sopfr[n_] := If[n == 1, 0, Total[Times @@@ FactorInteger[n]]]; %t A045835 Select[Range[1000], If[# == 1, True, sopfr[PrimeOmega[#]] == PrimeOmega[sopfr[#]]]&] (* _Jean-François Alcover_, Apr 06 2021 *) %Y A045835 Cf. A001222, A001414, A001248, A076361. %K A045835 nonn %O A045835 1,2 %A A045835 _Reinhard Zumkeller_, Mar 04 2003