%I A001273
%S A001273 1,10,13,23,19,7,356,78999
%N A001273 Smallest number that takes n steps to reach 1 under iteration of sum-of-squares-of-digits 
               map (the next term is 3788 followed by 973 9's and is too large to 
               include here).
%C A001273 Also known as the smallest happy numbers of height n.
%C A001273 a(8)= 3788 followed by 973 9's, a(9)= 237 followed by 4.6777777.......77777 
               x 10^974 9's - Sergio Pimentel (ferdiego(AT)suddenlink.net), Feb 
               21 2007
%D A001273 R. K. Guy, Unsolved Problems Number Theory, Sect. E34.
%Y A001273 Cf. A007770, A018785.
%Y A001273 Sequence in context: A129075 A095918 A018785 this_sequence A111524 A074346 
               A126973
%Y A001273 Adjacent sequences: A001270 A001271 A001272 this_sequence A001274 A001275 
               A001276
%K A001273 base,nonn
%O A001273 0,2
%A A001273 N. J. A. Sloane (njas(AT)research.att.com).
%E A001273 More terms from Jud McCranie (j.mccranie(AT)comcast.net) Sep 15 1994.