Search: id:A074905
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%I A074905
%S A074905 0,0,1,1,0,2,0,2,1,0,3,2,0,1,1,3,0,2,1,0,2,1,3,4,0,0,1,0,1,5,1,2,0,5,0,
%T A074905 1,3,1,0,2,0,3,0,1,0,7,7,1,0,0,2,0,2,2,2,2,0,1,1,0,2,7,1,0,1,7,2,3,0,0,
%U A074905 2,2,1,1,2,1,5,1,2,4,0,2,0,1,0,3,3,1,1,1,4,3,1,2,2,1,6,0,6,4,3,2,2,1,1
%N A074905 Number of integers with an even number of distinct primes (for which 
               mu(n)=1) between two consecutive primes p(n) and p(n+1).
%e A074905 Between 541 and 547 the 4 numbers which have an even number of distinct 
               primes are as follows: {542,543,545,546}, so a(100)=4.
%p A074905 readlib(issqr): sstmp := proc(n) local t1,i; t1 := 0; for i from ithprime(n) 
               to ithprime(n+1) do if (issqrfree(i) = 'true' and mobius(i)=1) then 
               t1 := t1+1; fi; od; t1; end: sstmp(200);
%Y A074905 Cf. A061265, A061399.
%Y A074905 Sequence in context: A127371 A036849 A097364 this_sequence A058548 A157030 
               A080844
%Y A074905 Adjacent sequences: A074902 A074903 A074904 this_sequence A074906 A074907 
               A074908
%K A074905 nonn
%O A074905 0,6
%A A074905 Jani Melik (jani_melik(AT)hotmail.com), Sep 30 2002

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