4 December

There are 5 ways to tile a 3×2 rectangle with 2×2 squares and 2×1 dominos.
Today's number is the number of ways to tile a 9×2 rectangle with 2×2 squares and 2×1 dominos.

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the only crossnumber sequences bases time graphs dominos chocolate circles mean hexagons volume doubling area triangles regular shapes 2d shapes dodecagons squares algebra clocks dice speed grids cryptic crossnumbers fractions unit fractions parabolas wordplay rectangles range integers geometry sums median differentiation ave pascal's triangle chalkdust crossnumber irreducible numbers balancing tiling remainders elections crossnumbers spheres calculus gerrymandering surds coordinates arrows rugby dates trigonometry crossnumber multiplication coins division partitions lines scales money cryptic clues addition numbers christmas triangle numbers cards digital clocks means star numbers routes digits people maths games 3d shapes ellipses complex numbers symmetry prime numbers sum to infinity advent folding tube maps colouring books number chess quadratics palindromes averages polygons shapes square numbers functions multiples integration crosswords perimeter sport square roots percentages indices proportion taxicab geometry factors angles odd numbers cube numbers factorials probability logic perfect numbers floors planes probabilty shape menace products


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