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Values of Moebius function of the products of two (not necessarily distinct) primes (semiprimes or 2-almost primes, A001358).
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%I #12 Oct 04 2017 14:02:03

%S 0,1,0,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,

%T 1,1,1,1,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,1,1,1,1,1,

%U 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1

%N Values of Moebius function of the products of two (not necessarily distinct) primes (semiprimes or 2-almost primes, A001358).

%C Characteristic function for numbers n such that A001358(n) is not a square. - _Antti Karttunen_, Oct 04 2017

%H Antti Karttunen, <a href="/A072165/b072165.txt">Table of n, a(n) for n = 1..3001</a>

%H Kimberly Schneider, <a href="http://planetmath.org/?op=getobj&amp;from=objects&amp;name=MoebiusFunction">Moebius function.</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%F a(n) = A008683(A001358(n)). - _Antti Karttunen_, Oct 04 2017

%e For n = 2995, A001358(2995) = 11449 = 107^2, and as Moebius mu is zero for squares, we have a(2995) = 0. - _Antti Karttunen_, Oct 04 2017

%p semiprimes := proc(d_n) local a,i; a := [ ]; for i from 1 to d_n do if((tau(i) = 3) or ((mobius(i) <> 0) and (tau(i) = 4))) then a := [ op(a), mobius(i) ]; fi; od: RETURN(a); end;

%Y Cf. A001358, A008683.

%K easy,nonn

%O 1,1

%A _Jani Melik_, Jun 28 2002

%E More terms from _Antti Karttunen_, Oct 04 2017