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Old 2021-06-01, 16:17   #23
charybdis
 
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Apr 2020

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Nicely done!

Quote:
Originally Posted by bsquared View Post
At the risk of increasing confusion, I ran this through yafu's poly select and it slightly prefers the other degree 5:
Yes:

Quote:
Originally Posted by charybdis View Post
You could also represent this number as 8*1281979*2^520+1, giving c5 = 10255832, c0 = 1, Y1 = 1, Y0 = -2^104. This choice of polynomial might even be slightly faster than yours; at least it has a higher E-score. For some numbers there will be even more polynomials to choose between: this will often be the case when near the crossover between degree 5 and degree 6, for instance (and here we have to test-sieve, as E-scores from different degrees are not comparable).
I suggested sieving on the rational side but YAFU just about prefers algebraic side for this polynomial - for a larger number this would call for test-sieving. k*2^n+1 would be a rational side job for the usual small values of k (e.g. 1) but as k gets bigger so do the algebraic norms.
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