%I A003621 M4764
%S A003621 0,1,11,0,8,13,5,9,10,1,2,9,2,10,10,7,9,9,4,1,9,10,3,2,7,9,10,3,6,11,2,
%T A003621 3,10,8,9,12,6,7,11,8,10,2,8,4,11,8,9,10,4,8,10,7,9,11,9,8,10,5,8,13,7,
%U A003621 9,12,8,8,11,6,2,12,5,9,10,6,9,10,6,5,4,3,9
%N A003621 Number of iterations until n reaches 1 or 4 under x goes to sum of squares 
               of digits map.
%D A003621 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A003621 A. Porges, A set of eight numbers, Amer. Math. Monthly, 52 (1945), 379-382.
%D A003621 J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 13.
%Y A003621 A000216, A000218, etc.
%Y A003621 Sequence in context: A110408 A138066 A115595 this_sequence A055963 A127805 
               A088621
%Y A003621 Adjacent sequences: A003618 A003619 A003620 this_sequence A003622 A003623 
               A003624
%K A003621 nonn,base
%O A003621 1,3
%A A003621 N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein