%I A121385
%S A121385 0,0,0,0,0,0,0,0,1,1,2,2,3,4,5,6,7,8,10,12,14,16,18,20,22,24,26,28,31,
%T A121385 34,37,40,43,46
%N A121385 Minimal number of three-term arithmetic progressions that a coloring 
               of {1,...,n} can contain.
%C A121385 a(9)=1 is the well known fact that the van der Waerden number for 2 colors 
               and three-term arithmetic progressions is 9.
%e A121385 a(8)=0 because we can two color {1,...,8} by 11001100 so that there are 
               no three-term arithmetic progressions.
%Y A121385 Cf. A121386.
%Y A121385 Sequence in context: A089197 A017874 A029016 this_sequence A029015 A000008 
               A001312
%Y A121385 Adjacent sequences: A121382 A121383 A121384 this_sequence A121386 A121387 
               A121388
%K A121385 nonn
%O A121385 1,11
%A A121385 Steve Butler (sbutler(AT)math.ucsd.edu), Jul 26 2006