■数とあそぶ(その25)

 πの連分数展開は

  π=[3:7,15,1,292,・・・]

 これから,近似値

  3,22/7,333/106,355/113,103993/33102,・・・

が得られる.

 √2の連分数展開は

  √2=[1:2,2,2,2,・・・]

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  2π√2=8.88576→8

  1/.88576=1.12898→1

  1/.12898=7.75338→7

  1/.75338=・・・

を続けると

  [8:1,7,1,3,15,1,1,3,3,2,・・・]

8+1/(1+1/7)=8+7/8

8+1/(1+1/(7+1/1))=8+8/9

8+1/(1+1/(7+1/(1+1/3)))=8+31/35

8+1/(1+1/(7+1/(1+1/(3+1/15))))=8+473/519

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