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RE: pseudo idea; I'll try again!

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  • Bill Bouris
    no more posts for a while... proofreading is hectic here s how to catch a 2-pseudoprime... if `I is already prime, then the algorithm lets it slip through;
    Message 1 of 1 , Feb 19, 2008
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      no more posts for a while... proofreading is hectic

      here's how to catch a 2-pseudoprime...

      if `I' is already prime, then the algorithm lets it
      slip through; but...
      if `I' is a pseudo-prime, then it catches it before
      saying it's prime!

      is my idea creative enough ??? can someone verify it
      ??? my computer is very, very primitive

      the method below is unproven, but not unfounded... and
      a bit much to take in...

      10 CLS
      15 FOR I= 7 TO 2001
      20 IF 2^(I-1) MOD I= 1 THEN //the usual 2-PRP test
      25 Y= 2^(((I-1)/2)-3) MOD I
      30 YY= I MOD 4
      32 // check for pseudoprime before saying the
      num-ber is prime!
      35 IF YY= 1 AND ((Y=> I*1/8 AND Y<= I*1/2) OR (Y=>
      I*3/4 AND Y<= I*7/8)) THEN

      40 PRINT I, "composite"
      45 END IF
      50 IF YY= 3 AND (Y<= I*1/8 OR (Y>= I*1/2 AND Y<=
      I*3/4) OR Y>= I*7/8) THEN

      55 PRINT I, "composite"
      60 ELSE PRINT I, "prime"
      65 END IF
      70 SLEEP 1
      75 END IF
      80 NEXT I

      Bill B.



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