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A056170
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Number of non-unitary prime divisors of n.
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14
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0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 2, 0, 0, 0, 1, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,36
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COMMENTS
| Number of prime squares dividing n. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 18 2002
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FORMULA
| A prime factor of n is unitary iff its exponent is 1 in the prime factorization of n. (Of course for any prime p, GCD(p, n/p) is either 1 or p. For a unitary prime factor it must be 1.)
Additive with a(p^e) = 0 if e = 1, 1 otherwise.
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MATHEMATICA
| a[n_] := Count[FactorInteger[n], {_, k_ /; k > 1}]; Table[a[n], {n, 105}] (* Jean-François Alcover Mar 23 2011 *)
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CROSSREFS
| A034444, A001221.
Cf. A057427(a(n)) = 1 - A008966(n).
Cf. A048105.
Sequence in context: A093956 A160383 A101436 * A059483 A067618 A055029
Adjacent sequences: A056167 A056168 A056169 * A056171 A056172 A056173
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KEYWORD
| nice,nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Jul 27 2000
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EXTENSIONS
| Minor edits by Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Mar 23 2011
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