This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A140650 #9 Mar 29 2014 03:06:32 %S A140650 0,3,48,600,32256,1177344,268369920,36506664960,35184338534400, %T A140650 18577347909255168,73786976226118729728,153476910691030086451200, %U A140650 2475880078570197599844827136,20440865928680162788862343512064,1329227995784915854457062986570792960 %N 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. %F A140650 a(2n) = 2^(2n^2-1)*(2^n+1)-2^(n^2-1)*(2^n+1). %F A140650 a(2n+1) = 2^(2n^2+3n+1)-2^(n^2+2n+1). (corrected by _Colin Barker_, Mar 28 2014) %o A140650 (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 %Y A140650 Cf. A054257, A054407. %K A140650 nonn %O A140650 1,2 %A A140650 _Anthony C Robin_, Jul 09 2008 %E A140650 More terms from _Colin Barker_, Mar 28 2014