%I A005229 M0441
%S A005229 1,1,2,3,3,4,5,6,6,7,7,8,9,10,10,11,12,12,13,14,15,16,16,17,17,
%T A005229 18,19,19,20,20,21,22,23,24,24,25,26,26,27,28,29,29,30,30,30,31,
%U A005229 32,33,34,35,36,36,37,37,38,39,39,40,41,42,43,43,44,45,45,45,46
%N A005229 a(1)=a(2)=1; for n>2, a(n)=a(a(n-2))+a(n-a(n-2)).
%C A005229 By induction a(n)<=n, but exact rate of growth is not known.
%D A005229 J. Arkin, D. C. Arney, L. S. Dewald and W. E. Ebel, Jr., Families of 
               recursive sequences, J. Rec. Math., 22 (No. 22, 1990), 85-94.
%D A005229 C. L. Mallows, Conway's challenge sequence, Amer. Math. Monthly, 98 (1991), 
               5-20.
%D A005229 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%H A005229 T. D. Noe, <a href="b005229.txt">Table of n, a(n) for n=1..1000</a>
%H A005229 Nick Hobson, <a href="a005229.py.txt">Python program for this sequence</
               a>
%H A005229 N. J. A. Sloane, <a href="http://www.research.att.com/~njas/doc/sg.txt">
               My favorite integer sequences</a>, in Sequences and their Applications 
               (Proceedings of SETA '98).
%H A005229 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               MallowsSequence.html">Link to a section of The World of Mathematics.</
               a>
%p A005229 A005229 := proc(n) option remember; if n<=2 then 1 else A005229(A005229(n-2))+A005229(n-A005229(n-2)); 
               fi; end;
%o A005229 (PARI) a(n)=an[ n ]; an=vector(100,n,1); for(n=3,100,an[ n ]=a(a(n-2))+a(n-a(n-2)))
%Y A005229 Cf. A004001, A051105.
%Y A005229 Sequence in context: A006161 A132351 A025556 this_sequence A091245 A100618 
               A061288
%Y A005229 Adjacent sequences: A005226 A005227 A005228 this_sequence A005230 A005231 
               A005232
%K A005229 nonn,nice,easy
%O A005229 1,3
%A A005229 N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
%E A005229 Typo in definition corrected by Nick Hobson, Feb 21 2007