A072165 Values of Moebius function of the products of two (not necessarily distinct) primes (semiprimes or 2-almost primes, A001358).

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, 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, 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

Offset: 1

Author

Jani Melik, Jun 28 2002

Keywords

• easy
• nonn

Comments

Characteristic function for numbers n such that A001358(n) is not a square. - Antti Karttunen, Oct 04 2017

Examples

			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
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..3001
• Kimberly Schneider, Moebius function.
• Index entries for characteristic functions

Crossrefs

Cf. A001358, A008683.

Programs

Maple

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;

Formula

a(n) = A008683(A001358(n)). - Antti Karttunen, Oct 04 2017

Extensions

More terms from Antti Karttunen, Oct 04 2017