%I A087777
%S A087777 1,1,1,1,2,4,6,7,7,5,3,8,9,11,12,9,9,13,11,9,13,16,13,19,16,11,14,16,21,
%T A087777 22,14,14,19,17,22,27,25,16,20,28,22,22,26,25,24,32,26,22,29,29,32,35,
               32,
%U A087777 27,26,34,30,33,40,25,27,46,40,33,32,28,36,50,44,31,36,38,46,53,41,29,
               41
%N A087777 a(1) = ... = a(4) = 1; a(n)=a(n-a(n-2))+a(n-a(n-4)).
%C A087777 It is not known if this sequence is defined for all positive n. Balamohan 
               et al. comment that it shows "inscrutably wild behavior".
%H A087777 N. J. A. Sloane, <a href="b087777.txt">Table of n, a(n) for n = 1..10000</
               a>
%H A087777 B. Balamohan, A. Kuznetsov and S. Tanny, <a href="http://www.cs.uwaterloo.ca/
               journals/JIS/index.html">On the behavior of a variant of Hofstadter's 
               Q-sequence</a>, J. Integer Sequences, Vol. 10 (2007), #07.7.1.
%H A087777 <a href="Sindx_Ho.html#Hofstadter">Index entries for Hofstadter-type 
               sequences</a>
%p A087777 a := proc(n) option remember; if n<=4 then 1 else if n > a(n-2) and n 
               > a(n-4) then RETURN(a(n-a(n-2))+a(n-a(n-4))); else ERROR(" died 
               at n= ", n); fi; fi; end;
%Y A087777 Cf. A005185, A063882, A046700.
%Y A087777 Sequence in context: A114431 A167689 A058184 this_sequence A030118 A023835 
               A138888
%Y A087777 Adjacent sequences: A087774 A087775 A087776 this_sequence A087778 A087779 
               A087780
%K A087777 nonn
%O A087777 1,5
%A A087777 Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Oct 05 2003
%E A087777 Edited by N. J. A. Sloane (njas(AT)research.att.com), Nov 06 2007