%I A011921
%S A011921 0,0,0,0,2,10,32,76,152,274,458,720,1080,1560,2184,2978,
%T A011921 3970,5192,6676,8456,10570,13058,15960,19320,23184,27600,
%U A011921 32618,38290,44672,51820,59792,68650,78458,89280,101184
%N A011921 [ n(n-1)(n-2)(n-3)/11 ].
%Y A011921 Sequence in context: A051747 A024456 A050927 this_sequence A103290 A131068 
               A034555
%Y A011921 Adjacent sequences: A011918 A011919 A011920 this_sequence A011922 A011923 
               A011924
%K A011921 nonn
%O A011921 0,5
%A A011921 N. J. A. Sloane (njas(AT)research.att.com).