OFFSET
1,2
COMMENTS
EXAMPLE
a(1) = 1 is in this sequence since omega(1) = 0 = omega(2^1-1). Elements of A000043 are primes p such that 2^p-1, they are in this sequence since omega(p) = 1 = omega(2^p-1). a(5) = 6 is in this sequence since omega(6) = #{2,3} = 2 = omega(2^6-1) = #{3,7}.
MATHEMATICA
Select[Range[700], PrimeNu[#]==PrimeNu[2^#-1]&] (* Harvey P. Dale, Jan 04 2018 *)
PROG
(PARI) is_A144671(n)={ omega(n)==omega(2^n-1) }
CROSSREFS
KEYWORD
more,nonn
AUTHOR
M. F. Hasler, Feb 01 2009
EXTENSIONS
Two more terms from Max Alekseyev, Apr 27 2010
STATUS
approved