A140650 Number of different ways of coloring an n X n grid of squares using two colors so that the resulting grid has just one line of symmetry.
0, 3, 48, 600, 32256, 1177344, 268369920, 36506664960, 35184338534400, 18577347909255168, 73786976226118729728, 153476910691030086451200, 2475880078570197599844827136, 20440865928680162788862343512064, 1329227995784915854457062986570792960
Offset: 1
Keywords
Programs
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PARI
s=[0]; for(n=1, 10, s=concat(s, [2^(2*n^2-1)*(2^n+1)-2^(n^2-1)*(2^n+1), 2^(2*n^2+3*n+1)-2^(n^2+2*n+1)])); s \\ Colin Barker, Mar 28 2014
Formula
a(2n) = 2^(2n^2-1)*(2^n+1)-2^(n^2-1)*(2^n+1).
a(2n+1) = 2^(2n^2+3n+1)-2^(n^2+2n+1). (corrected by Colin Barker, Mar 28 2014)
Extensions
More terms from Colin Barker, Mar 28 2014