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 A143519 Moebius transform of A010051, the characteristic function of the primes: a(n) = Sum_{d|n} mu(n/d)*A010051(d); A054525 * A010051. 7
 0, 1, 1, -1, 1, -2, 1, 0, -1, -2, 1, 1, 1, -2, -2, 0, 1, 1, 1, 1, -2, -2, 1, 0, -1, -2, 0, 1, 1, 3, 1, 0, -2, -2, -2, 0, 1, -2, -2, 0, 1, 3, 1, 1, 1, -2, 1, 0, -1, 1, -2, 1, 1, 0, -2, 0, -2, -2, 1, -1, 1, -2, 1, 0, -2, 3, 1, 1, -2, 3, 1, 0, 1, -2, 1, 1, -2, 3, 1, 0, 0, -2, 1, -1, -2, -2, -2, 0, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS A010051 = A051731 * A143519 (since A051731 = the inverse Mobius transform). A000720(n) = Sum_{k=1..n} a(k) floor(n/k) where A000720(n) is the number of primes <= n. - Steven Foster Clark, May 25 2018 LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA Mobius transform of A010051, the characteristic function of the primes. Row sums of triangle A143518. a(n) = Sum_{d|n} A010051(d)*A008683(n/d). - Antti Karttunen, Jul 19 2017 EXAMPLE a(4) = -1 since row 4 of triangle A043518 = (0, -1, 0, 0). a(4) = -1 = (0, -1, 0, 1) dot (0, 1, 1, 0), where (0, -1, 0, 1) = row 4 of A054525 and A010051 = (0, 1, 1, 0, 1, 0, 1, 0, ...). MATHEMATICA Table[Sum[MoebiusMu[n/d] Boole[PrimeQ@ d], {d, Divisors@ n}], {n, 89}] (* Michael De Vlieger, Jul 19 2017 *) PROG (Sage) def A143519(n) :     D = filter(is_prime, divisors(n))     return add(moebius(n/d) for d in D) [A143519(n) for n in (1..89)]   # Peter Luschny, Feb 01 2012 (PARI) A143519(n) = sumdiv(n, d, isprime(d)*moebius(n/d)); \\ (After Luschny's Sage-code) - Antti Karttunen, Jul 19 2017 CROSSREFS Cf. A008683, A010051, A143518, A054525, A137851. Sequence in context: A203827 A194289 A237194 * A307778 A029376 A276790 Adjacent sequences:  A143516 A143517 A143518 * A143520 A143521 A143522 KEYWORD sign AUTHOR Gary W. Adamson, Aug 22 2008 EXTENSIONS More terms from R. J. Mathar, Jan 19 2009 STATUS approved

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Last modified June 16 07:14 EDT 2019. Contains 324145 sequences. (Running on oeis4.)