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A093318
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d(n) = number of positive divisors k of n where mu(k) = 1 and mu(n/k) = -1.
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0
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0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 4, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 4, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 4, 1, 1, 0, 4, 1, 0, 1, 0, 1, 1, 0, 4, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,30
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FORMULA
| 4*d(n) + sum{k|n} mu(k)*mu(n/k) = product{p|n} e(p, n), where the product is over the distinct primes dividing n; e(p, n) = 2 if p|n but p^2 does not divide n; e(p, n) = 1 if p^2|n but p^3 does not divide n; e(p, n) = 0 if p^3|n.
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CROSSREFS
| Cf. A008683 (for mu).
Sequence in context: A013464 A051390 A124120 * A127560 A098172 A049759
Adjacent sequences: A093315 A093316 A093317 * A093319 A093320 A093321
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KEYWORD
| nonn,easy
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AUTHOR
| Leroy Quet Apr 26 2004
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EXTENSIONS
| More terms from Pab Ter (pabrlos(AT)yahoo.com), May 24 2004
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