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 A074823 a(n) = 2^omega(n)*mu(n)^2. 6
 1, 2, 2, 0, 2, 4, 2, 0, 0, 4, 2, 0, 2, 4, 4, 0, 2, 0, 2, 0, 4, 4, 2, 0, 0, 4, 0, 0, 2, 8, 2, 0, 4, 4, 4, 0, 2, 4, 4, 0, 2, 8, 2, 0, 0, 4, 2, 0, 0, 0, 4, 0, 2, 0, 4, 0, 4, 4, 2, 0, 2, 4, 0, 0, 4, 8, 2, 0, 4, 8, 2, 0, 2, 4, 0, 0, 4, 8, 2, 0, 0, 4, 2, 0, 4, 4, 4, 0, 2, 0, 4, 0, 4, 4, 4, 0, 2, 0, 0, 0, 2, 8, 2, 0, 8 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA Sum_{k=1..n} a(k) = A069201(n). Multiplicative with a(p)=2, a(p^e)=0, e > 1. a(n) = A034444(n)*A008966(n). - R. J. Mathar, Apr 15 2011 Sum_{n>0} a(n)/n^s = Product_{p prime} (1 + 2p^(-s)). - Ralf Stephan, Jul 07 2013 a(n) = abs(A226177(n)). - Antti Karttunen, Jul 23 2017 PROG (Scheme) (define (A074823 n) (if (= 1 n) n (* (if (= 1 (A067029 n)) 2 0) (A074823 (A028234 n))))) ;; Antti Karttunen, Jul 23 2017 (PARI) a(n) = 2^omega(n)*moebius(n)^2; \\ Michel Marcus, Jul 23 2017 CROSSREFS Cf. A001221, A008683, A008966, A034444, A069201, A226177. Sequence in context: A105673 A259761 A171933 * A226177 A159916 A159286 Adjacent sequences:  A074820 A074821 A074822 * A074824 A074825 A074826 KEYWORD mult,nonn AUTHOR Benoit Cloitre, Sep 08 2002 EXTENSIONS Additional comments from Vladeta Jovovic, Dec 30 2002 STATUS approved

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Last modified May 16 23:46 EDT 2021. Contains 343957 sequences. (Running on oeis4.)