%I A008794
%S A008794 0,0,1,1,4,4,9,9,16,16,25,25,36,36,49,49,64,64,81,81,100,100,
%T A008794 121,121,144,144,169,169,196,196,225,225,256,256,289,289,
%U A008794 324,324,361,361,400,400,441,441,484,484,529,529,576,576
%N A008794 Squares repeated.
%C A008794 Also number of non-attacking kings on n-2 X n-2 board (cf. A030978). 
               - Koksal Karakus (karakusk(AT)hotmail.com), May 27 2002
%C A008794 Maximum number of 2 X 2 tiles that fit on an n X n board. - Jon Perry 
               (perry(AT)globalnet.co.uk), Aug 10 2003
%C A008794 (n)-(1) + (n-1) -(2) +(n-3)-(3)+ ... + (n-r) -(r)... n terms. e.g. 5-1+4-2+3=9 
               6-1+5-2+4-3=9 7-1+6-2+5-3+4 =16 8-1+7-2+6-3+5-4=16 - Amarnath Murthy 
               (amarnath_murthy(AT)yahoo.com), Jul 24 2005
%C A008794 The smallest possible number of white cells in a solution to an n X n 
               nurikabe grid. [From Tanya Khovanova (tanyakh(AT)yahoo.com), Feb 
               24 2009]
%H A008794 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               KingsProblem.html">Link to a section of The World of Mathematics.</
               a>
%F A008794 a(n)=[floor(n/2)]^2
%F A008794 a(n)=(2n-1)(-1)^n/8+(2n^2-2n +1)/8; a(n+1)=sum{k=0..n, k(1-(-1)^k)/2}. 
               - Paul Barry (pbarry(AT)wit.ie), May 31 2003
%F A008794 a(n)={sqrt[sum_{j=0..n}(j+1)*(cos(j*Pi)+1)/2]-1}^2 with n>=0. - Paolo 
               P. Lava (ppl(AT)spl.at), Dec 04 2006
%p A008794 G.f.: x^2*(1+x^2)/((1-x^2)^2*(1-x)).
%Y A008794 Cf. A086832.
%Y A008794 Sequence in context: A014694 A065730 A145445 this_sequence A075709 A116682 
               A088190
%Y A008794 Adjacent sequences: A008791 A008792 A008793 this_sequence A008795 A008796 
               A008797
%K A008794 nonn
%O A008794 0,5
%A A008794 N. J. A. Sloane (njas(AT)research.att.com).