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Sum

What is
$$\sum_{i=1}^{\infty}\frac{1}{i 2^i}$$
?

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Sunday Afternoon Maths LXVII

Coloured weights
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Cryptic crossnumber #2

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

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