Search: id:A063982
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%I A063982
%S A063982 1,2,2,2,2,1,2,2,2,2,4,2,2,2,2,2,2,2,2,2,2,2,4,2,4,2,2,4,8,2,2,2,2,2,4,
%T A063982 4,4,2,4,2,4,2,8,4,4,2,8,4,2,4,8,8,8,2,8,2,4,4,4,4,2,2,4,4,2,4,4,8,2,4,
%U A063982 8,4,8,4,4,8,2,2,8,2,8,4,4,4,2,2,4,4,2,2,8,16,2,4,8,4,4,2,8,8
%N A063982 Number of divisors of 2^n - 1 that are relatively prime to 2^m - 1 for 
               all 0 < m < n.
%H A063982 Sam Wagstaff, Cunningham Project, <a href="http://www.cerias.purdue.edu/
               homes/ssw/cun/pmain501">Factorizations of 2^n-1, n odd, n<1200</a>
%e A063982 Divisors of 2^8-1 are {1, 3, 5, 15, 17, 51, 85, 255}, but only 1 and 
               17 are relatively prime to 2^m - 1 for all m < 8, thus a(8)=2.
%t A063982 a = {1}; Do[ d = Divisors[2^n - 1]; l = Length[d]; c = 0; k = 1; While[ 
               k < l + 1, If[ Union[ GCD[a, d[[k]] ]] == {1}, c++ ]; k++ ]; Print[c]; 
               a = Union[ Flatten[ Append[a, Transpose[ FactorInteger[2^n - 1]][[ 
               1]] ]]], {n, 1, 100} ]
%Y A063982 Cf. A064078.
%Y A063982 Sequence in context: A037200 A090044 A036238 this_sequence A055020 A052435 
               A094701
%Y A063982 Adjacent sequences: A063979 A063980 A063981 this_sequence A063983 A063984 
               A063985
%K A063982 nonn,nice
%O A063982 1,2
%A A063982 Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 06 2001
%E A063982 More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 10 2001

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