%I A141582
%S A141582 2,8,21,48,93,168,278,440,660,960,1347,1848,2471,3248,4188,5328,6678,
%T A141582 8280,10145,12320,14817,17688,20946,24648,28808,33488,38403,44520,50955,
%U A141582 58080,65912,74528,83946,94248
%N A141582 a(n)= number of ways to dispose two pawns on a chessboard of size n X 
               n (two dispositions are equivalent if one can be rotated or reflected 
               to give the other one).
%F A141582 For n even, a(n) = n * (n^3 + 6*n -4) / 16 for n odd a(n) = (n^2-1) * 
               (n^2 + 7) / 16
%e A141582 For n = 2, two ways : either two pawns on any edge, or two pawns on any 
               diagonal, hence a(2)=2
%Y A141582 Sequence in context: A090612 A051744 A062443 this_sequence A000160 A034519 
               A014409
%Y A141582 Adjacent sequences: A141579 A141580 A141581 this_sequence A141583 A141584 
               A141585
%K A141582 easy,nonn
%O A141582 0,1
%A A141582 Philippe Lallouet (philip.lallouet(AT)orange.fr), Aug 19 2008