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Thread: Triangular,squre,pentagonal number

  1. April 21st 2009, 07:20 AM #1
    chipai
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    Triangular,squre,pentagonal number

    Is there a number,aside from 1,simultaneously triangular,squre,pentagonal number ?
    that is, is there a L=(3n^2-n)/2=(k^2+k)/2=m^2
    for some m,n,k are positive integers.
    Last edited by chipai; April 22nd 2009 at 10:10 AM.
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  2. April 30th 2009, 12:12 PM #2
    Media_Man
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    Pentagonal Square Triangular Number -- from Wolfram MathWorld
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