عدد مثلثي: الفرق بين النسختين

* [http://www.cut-the-knot.org/do_you_know/numbers.shtml#square Triangular numbers] at [[cut-the-knot]]

* [http://www.cut-the-knot.org/do_you_know/triSquare.shtml There exist triangular numbers that are also square] at [[cut-the-knot]]

 

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