OFFSET
1,2
COMMENTS
Omega(n) is the number of prime divisors of n, A001222 (for n>0), taking Omega(0)=0.
Omega(a(n)) >= 3 for n >= 5. - Robert Israel, Jul 04 2019
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1)=1 because Omega(1) = Omega(1 - (digital sum of 1)) = Omega(0) = 0;
a(2)=10 because Omega(10) = Omega(10 - (digital sum of 10)) = Omega(9) = 2.
MAPLE
filter:= proc(n) uses numtheory:
bigomega(n) = bigomega(n - convert(convert(n, base, 10), `+`))
end proc:
select(filter, [$1..500]); # Robert Israel, Jul 04 2019
MATHEMATICA
Join[{1}, Select[Range[2, 400], PrimeOmega[#]==PrimeOmega[#-Total[ IntegerDigits[ #]]]&]] (* Harvey P. Dale, Jun 21 2021 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Juri-Stepan Gerasimov, Nov 21 2010
EXTENSIONS
Corrected and edited by D. S. McNeil, Nov 21 2010
STATUS
approved