- **Conjectures 'R Us**
(*https://www.mersenneforum.org/forumdisplay.php?f=81*)

- - **Sierpinski / Riesel - Base 22**
(*https://www.mersenneforum.org/showthread.php?t=6916*)

small succes:
91268055041 | 22^134217728+1 So at least THAT one isn't prime :) |

[QUOTE=michaf;96539]small succes:
91268055041 | 22^134217728+1 So at least THAT one isn't prime :)[/QUOTE] That's about one millionth of a second's work. Why is it considered a success? |

[QUOTE=fatphil;96571]That's about one millionth of a second's work. Why is it considered a success?[/QUOTE]
He's probably thinking of how long it would take to test the number for primality if it hadn't been sieved. |

[QUOTE=jasong;96577]He's probably thinking of how long it would take to test the number for primality if it hadn't been sieved.[/QUOTE]
That was indeed what I was thinking :) _and_ it took some 24 hours to get to that sieving point :> |

[QUOTE=michaf;96590]That was indeed what I was thinking :)
_and_ it took some 24 hours to get to that sieving point :>[/QUOTE] Should have taken you less than a sec!:smile: Anyway why are you trying to factorize these numbers For base 22, numbers that are multiple of 22 do not have to be tested, this eliminates k=22,484 but k=1 is left. But 1*22^1+1 is prime hence 1 is eliminated. under base=100 only the following bases are left for which k does not produce a prime 38 50 62 68 86 92 98 You can try to find a prime for them |

[quote]
Originally Posted by michaf View Post Without any math skills... so excuse me if I bugger here :> base 22: 22*22^n + 1 = 22^(n+1) + 1 = 1*22^(n+1) + 1 so, k = 1 and that one is eliminated, therefore is k=22 and 484?[/quote] [quote] Unfortunately not. 1*22^1+1=23 prime, but, I think we decided for the Sierpinski base 5 exercise, that we would not use n=0, otherwise k=22 could be eliminated but not 484.[/quote] (quotes from sierpinski 6-18 thread) I think this justifies the search |

[QUOTE=Citrix;96592]Should have taken you less than a sec!:smile:
[/QUOTE] Oh, how do you do that? Test for all factors upto that limit in a sec? :) Or did you mean just testing if that one number divided the huge number? |

[QUOTE=michaf;96643]Oh, how do you do that? Test for all factors upto that limit in a sec? :)
Or did you mean just testing if that one number divided the huge number?[/QUOTE] Finding the factor should take less than 1 sec. Try to factor 1 number at a time. What numbers are left, I can try to prove them composite them for you. |

Hmm... what am I doing wrong then?
srsieve is sieving about 20-30Million p's per second, but not a huge amount more when sieving only 1 n. Or is srsieve the wrong program here? |

[QUOTE=michaf;96674]Hmm... what am I doing wrong then?
srsieve is sieving about 20-30Million p's per second, but not a huge amount more when sieving only 1 n. Or is srsieve the wrong program here?[/QUOTE] Try PFGW. |

[QUOTE=Citrix;96679]Try PFGW.[/QUOTE]
I couldn't notice anything quicker about pfgw's factoring routines then there is in srsieve (quite the opposite, actually). What's pfgw's command to find "91268055041 | 22^134217728+1" quickly? |

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