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%I #8 Mar 30 2012 18:35:38
%S 2,6,8,14,26,62,134,393,1257,4659,9314,27933,167073,334142,4677862,
%T 14033577,56134292,2133102298,11788191218,52541651594
%N Least number which becomes prime or 4 after exactly n iterations of f(x) = sum of prime factors of x.
%C f(x) = sum of prime factors with multiplicity, so that f(1500) = 2+2+3+5+5+5 = 22.
%C Identical to the different-offset A121360 except for the second term. - Hans Havermann, Oct 05 2010
%C a(20) <= 536226160966. a(21) <= 2681130804805. a(22) <= 8512643845707. - Donovan Johnson
%K nonn
%O 0,1
%A _David W. Wilson_
%E a(17) from _Donovan Johnson_, Apr 25 2010
%E Edited comment and a(18)-a(19) from _Donovan Johnson_, Oct 16 2010
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