Monthly Archives: March 2014

Triangle whose sides and area are integers, semiperimeter a square

      Update :              

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x^2 – y^2 = A^3 and x^3 – y^3 = B^2

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Integer triangles, sides form an arithmetical progression

  For example,       Find others.                

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Factors of 7*2^n – 1

  Related posts: k * 2^n ± 1 Factors of   3 * 2^n – 1,   n=1,2,..,100 Factors of 5 * 2^n – 1            

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Primitive Pythagorean triples (a, b, c) with c – a = 8

           

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Factors of 5*2^n – 1

           

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Consecutive num3ers that are not divisible by any of their digits

  I’m presenting a sequence of consecutive integers which are not divisible by any of their digits:   2-digit numbers :   3-digit numbers :     The first square number in that sequence :   The first twin prime … Continue reading

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Pattern – Divisibility | Repunit

               

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Square Num3ers that end with xyxyxyxyxy

  To find the smallest square numbers that end with:                              2121212121                              2929292929                              6969696969                              8484848484            

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Integer n such that n+6 is prime and 9*n + k a square

  Find the first few values for   n   so that   n + 6   is a prime number and (9*n + 8),   (9*n + 7),   (9*n + 6), …   (9*n + 1)   are … Continue reading

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