%I A005350 M0253
%S A005350 1,1,1,2,2,3,3,3,4,5,5,5,5,6,7,7,8,8,8,8,8,9,10,11,11,12,
%T A005350 12,12,13,13,13,13,13,13,14,15,16,16,17,18,18,19,19,19,20,
%U A005350 20,20,20,21,21,21,21,21,21,21,22,23,24,25,25,26,27,27,28
%N A005350 a(1) = a(2) = a(3) = 1, a(n) = a(a(n-1))+a(n-a(n-1)) for n >= 4.
%C A005350 a(n)-a(n-1) = 0 or 1 (see the 1991 Monthly reference). - Emeric Deutsch 
               (deutsch(AT)duke.poly.edu), Jun 06 2005
%D A005350 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A005350 R. K. Guy, The second strong law of small numbers. Math. Mag. 63 (1990), 
               no. 1, 3-20.
%D A005350 Problem E3274, Amer. Math. Monthly, 98, No, 10, (1991), 958-959.
%H A005350 T. D. Noe, <a href="b005350.txt">Table of n, a(n) for n=1..1000</a>
%p A005350 A005350 := proc(n) option remember; if n<=3 then 1 else A005350(A005350(n-1))+A005350(n-A005350(n-1)); 
               fi; end;
%p A005350 a[1]:=1: a[2]:=1: a[3]:=1: for n from 4 to 64 do a[n]:=a[a[n-1]]+a[n-a[n-1]] 
               od: seq(a[n],n=1..64); (Deutsch)
%Y A005350 Cf. A004001, A005707.
%Y A005350 Sequence in context: A166079 A080677 A153112 this_sequence A055037 A125186 
               A140473
%Y A005350 Adjacent sequences: A005347 A005348 A005349 this_sequence A005351 A005352 
               A005353
%K A005350 nonn,easy,nice
%O A005350 1,4
%A A005350 N. J. A. Sloane (njas(AT)research.att.com), R. K. Guy