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24672Re: many 1+1+1+2 selfridge tests [quartic puzzle]

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  • djbroadhurst
    Nov 22, 2012
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      --- In primenumbers@yahoogroups.com,
      paulunderwooduk" <paulunderwood@...> wrote:

      > At least one of the evaluations of x at -1,1,0,-2 or 2
      > should be -1,1,0,-2, or 2

      Here are some scores out of 5:

      {A(k,x)=sum(j=0,k/2,(-1)^j*binomial(k-j,j)*x^(k-2*j));}
      {B(k,x)=sum(j=0,(k-1)/2,(-1)^j*binomial(k-j-1,j)*x^(k-2*j-1));}
      {L=[-1,1,0,-2,2];S=Set(L);for(k=2,40,f=factor(A(k,x)-B(k,x))[,1];
      g=f[#f];c=0;for(j=1,#L,if(setsearch(S,subst(g,x,L[j])),c++));
      print1(c","));}

      4,4,3,4,4,4,4,4,4,4,4,3,4,4,4,5,4,4,4,4,5,4,4,4,4,5,4,4,4,5,5,4,4,4,4,4,5,4,3,

      David
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