%I A037271
%S A037271 2,1,13,2,4,1,5,4,4,1,15,1,1,2,3,4,4,1,2,2,1,5,3,2,2,1,9,2,9,6,1,15
%N A037271 Number of steps to reach a prime under "replace n by concatenation of 
               its prime factors", when applied to n-th composite number, or -1 
               if no such number.
%H A037271 P. De Geest, <a href="http://www.worldofnumbers.com/topic1.htm">Home 
               Primes</a>
%H A037271 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               HomePrime.html">Link to a section of The World of Mathematics.</a>
%e A037271 Starting with 14 (the seventh composite number) we get 14=2*7, 27=3*3*3, 
               333=3*3*37, 3337=47*71, 4771=13*367, 13367 is prime; so a(7)=5.
%Y A037271 Cf. A037271-A037274, A056938.
%Y A037271 Sequence in context: A009483 A124916 A007418 this_sequence A074955 A143663 
               A064079
%Y A037271 Adjacent sequences: A037268 A037269 A037270 this_sequence A037272 A037273 
               A037274
%K A037271 nonn,nice,base,hard
%O A037271 1,1
%A A037271 Jeff Burch (gburch(AT)erols.com)
%E A037271 Starting with 49, no prime has been reached after 79 steps.