

Proofs without words - TriinT
http://mathoverflow.net/questions/8846/proofs-without-words

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jgrahamc
Similar: [http://www.jgc.org/blog/2008/02/sum-of-first-n-odd-
numbers-i...](http://www.jgc.org/blog/2008/02/sum-of-first-n-odd-numbers-is-
always.html)

