%I #16 Jun 21 2021 15:30:19

%S 1,10,14,15,20,27,28,30,40,50,52,60,70,75,76,78,80,90,102,105,112,124,

%T 125,132,135,136,140,164,165,176,182,186,188,204,212,224,232,234,248,

%U 252,264,273,275,279,280,290,292,306,308,315,328,336,343

%N Numbers n such that Omega(n) = Omega(n - (digital sum of n)).

%C Omega(n) is the number of prime divisors of n, A001222 (for n>0), taking Omega(0)=0.

%C Omega(a(n)) >= 3 for n >= 5. - _Robert Israel_, Jul 04 2019

%H Robert Israel, <a href="/A172509/b172509.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1)=1 because Omega(1) = Omega(1 - (digital sum of 1)) = Omega(0) = 0;

%e a(2)=10 because Omega(10) = Omega(10 - (digital sum of 10)) = Omega(9) = 2.

%p filter:= proc(n) uses numtheory:

%p bigomega(n) = bigomega(n - convert(convert(n,base,10),`+`))

%p end proc:

%p select(filter, [$1..500]); # _Robert Israel_, Jul 04 2019

%t Join[{1},Select[Range[2,400],PrimeOmega[#]==PrimeOmega[#-Total[ IntegerDigits[ #]]]&]] (* _Harvey P. Dale_, Jun 21 2021 *)

%Y Cf. A001222.

%K nonn,base

%O 1,2

%A _Juri-Stepan Gerasimov_, Nov 21 2010

%E Corrected and edited by _D. S. McNeil_, Nov 21 2010