%I A131388
%S A131388 1,2,4,3,6,10,8,5,11,7,12,19,14,22,16,9,18,28,20,31,21,33,24,13,26,40,
%T A131388 27,15,30,46,32,17,34,52,36,55,38,58,39,60,42,64,44,23,47,25,48,73,50,
%U A131388 76,51,78,54,82,56,29,59,88,57,89,61,92,63,96,66,100,68,35,70,106,72,37
%N A131388 Conjectured permutation of the positive integers using Rule 1 with a(1)=1.
%C A131388 Conjecture 1: a( ) is a permutation of the positive integers. Conjecture 
               2: d( ) is a permutation of the integers. The sequence using "Rule 
               2" (positive before negative) is A131393.
%F A131388 Rule 1 ("negative before positive"): define sequences d( ) and a( ) as 
               follows: d(1)=0, a(1)=1 and for n>=2, d(n) is the greatest negative 
               integer d such that a(n-1)+d is not among a(1), a(2),...,a(n-1), 
               or, if no such d exists, then d(n) is the least positive integer 
               d such that a(n-1)+d is not among a(1), a(2),...,a(n-1). Then a(n)=a(n-1)+d.
%e A131388 a(2)=1+1, a(3)=a(2)+2, a(4)=a(3)+(-1), a(5)=a(4)+3, a(6)=a(5)+4.
%Y A131388 Cf. A131389, A131390, A131391, A131392, A131393, A131394, A131395, A131396, 
               A131397.
%Y A131388 Sequence in context: A113233 A051849 A083673 this_sequence A131393 A002326 
               A064273
%Y A131388 Adjacent sequences: A131385 A131386 A131387 this_sequence A131389 A131390 
               A131391
%K A131388 nonn
%O A131388 1,2
%A A131388 Clark Kimberling (ck6(AT)evansville.edu), Jul 05 2007