%I A087473
%S A087473 1,10,25,39,77,171,199,577,887,1592,2682,3988,6913,18747,39577,58439,
%T A087473 99428,173442,267343,299137,574182,685812,880543,1635812,1974447,
%U A087473 2771717,18871813,45797337,49899368,58935768
%N A087473 Smallest number that requires n iterations of f(k) to reach a single 
               digit, where f(k) is the product of the two numbers formed from the 
               alternating digits of k.
%e A087473 a(4)= 77 since 77 is the smallest number that requires 4 iterations to 
               reach a single digit: f(77)=7*7=49, f(49)=4*9=36, f(36)=3*6=18, f(18)=1*8=8.
%Y A087473 Cf. A087471, A087472, A087474.
%Y A087473 Sequence in context: A154057 A074814 A002600 this_sequence A014120 A003001 
               A038350
%Y A087473 Adjacent sequences: A087470 A087471 A087472 this_sequence A087474 A087475 
               A087476
%K A087473 nonn,base
%O A087473 0,2
%A A087473 Amarnath Murthy (amarnath_murthy(AT)yahoo.com) and Paul D. Hanna (pauldhanna(AT)juno.com), 
               Sep 11 2003
%E A087473 More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Sep 19 
               2003