%I A008133
%S A008133 0,0,0,1,1,2,4,4,6,9,9,12,16,16,20,25,25,30,36,36,42,49,
%T A008133 49,56,64,64,72,81,81,90,100,100,110,121,121,132,144,144,
%U A008133 156,169,169,182,196,196,210,225,225,240,256,256,272,289
%N A008133 floor(n/3)*floor((n+1)/3).
%F A008133 Partial sums of A087509. a(n+1)=sum{j=0..n, sum{k=0..j, if (mod(jk, 3)=2, 
               1, 0) }} - Paul Barry (pbarry(AT)wit.ie), Sep 14 2003
%Y A008133 Sequence in context: A000061 A153176 A112921 this_sequence A022471 A081238 
               A002086
%Y A008133 Adjacent sequences: A008130 A008131 A008132 this_sequence A008134 A008135 
               A008136
%K A008133 nonn
%O A008133 0,6
%A A008133 N. J. A. Sloane (njas(AT)research.att.com).