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Least numbers with n = digital root = number of prime factors.
0

%I #3 Mar 30 2012 18:50:19

%S 19,38,12,40,32,96,448,1664,1152

%N Least numbers with n = digital root = number of prime factors.

%C For 1 <= n <= 9: A010888(a(n)) = A001222(a(n)) = n.

%e a(7)=448 as A001222(448)=7 because of 448=2*2*2*2*2*2*7

%e and A010888(448)=7 because of 4+4+8=16 and 1+6=7.

%Y Cf. A007953.

%K nonn,base,fini,full

%O 1,1

%A _Reinhard Zumkeller_, Feb 19 2002