%I A124874
%S A124874 0,1,1,3,2,3,3,2,3,4,3,2,3,2,1,3,2,4,1,3,2,5,2,4,2,1,3,4
%N A124874 Number of primes dividing A007408(n).
%e A124874 a(1) = 0 since no prime divides A007408(1)=1,
%e A124874 a(2) = 1 since 3 is the only prime dividing A007408(2)=9,
%e A124874 a(3) = 1 since A007408(3)=251 is prime,
%e A124874 a(4) = 3 since A007408(4)=5 x 11 x 37,
%e A124874 a(6) = 3 since 7,11,53 are the only primes dividing A007408(6)=7^2 x 
               11 x 53.
%p A124874 seq( (nops@op)(2,(ifactors@A007408)(n)),n=1..25);
%Y A124874 Cf. A007408, A124876, A124877.
%Y A124874 Sequence in context: A153092 A165601 A054263 this_sequence A016459 A060585 
               A114451
%Y A124874 Adjacent sequences: A124871 A124872 A124873 this_sequence A124875 A124876 
               A124877
%K A124874 hard,nonn
%O A124874 1,4
%A A124874 M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 11 2006