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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. 1
0, 3, 48, 600, 32256, 1177344, 268369920, 36506664960, 35184338534400, 18577347909255168, 73786976226118729728, 153476910691030086451200, 2475880078570197599844827136, 20440865928680162788862343512064, 1329227995784915854457062986570792960 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..15.

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)

PROG

(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

CROSSREFS

Cf. A054257, A054407.

Sequence in context: A073982 A335178 A260347 * A081540 A294829 A264730

Adjacent sequences:  A140647 A140648 A140649 * A140651 A140652 A140653

KEYWORD

nonn

AUTHOR

Anthony C Robin, Jul 09 2008

EXTENSIONS

More terms from Colin Barker, Mar 28 2014

STATUS

approved

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Last modified October 19 08:46 EDT 2021. Contains 348074 sequences. (Running on oeis4.)