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Search: id:A107753
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| A107753 |
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Number of primitive subsets of the n-th roots of unity summing to zero. |
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+0
2
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| 1, 2, 2, 3, 2, 6, 2, 5, 4, 8, 2, 11, 2, 10, 9, 9, 2, 16, 2, 15, 11, 14, 2, 21, 6, 16, 10, 19, 2, 212, 2, 17, 15, 20, 13, 31, 2, 22, 17, 29, 2
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OFFSET
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1,2
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COMMENT
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A primitive subset has no nonempty proper subset whose members sum to zero. Note that a(30) is the first term for which the formulas do not apply. For n=30, there are 1,0,15,10,0,5,30,60,60,30 primitive subsets of size 0,1,2,...,9.
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FORMULA
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For primes p and q, if n = p^i, then a(n)=1+n/p; if n=p^i q^j, then a(n)=1+n/p+n/q.
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CROSSREFS
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Cf. A103314 (number of subsets of the n-th roots of unity summing to zero), A107754 (number of subsets of the n-th roots of unity summing to one).
Sequence in context: A015995 A068903 A108499 this_sequence A078224 A128710 A095757
Adjacent sequences: A107750 A107751 A107752 this_sequence A107754 A107755 A107756
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), May 23 2005
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