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1, -2, -2, 2, -2, 6, -2, -2, 2, 6, -2, -10, -2, 6, 6, 2, -2, -10, -2, -10, 6, 6, -2, 14, 2, 6, -2, -10, -2, -26, -2, -2, 6, 6, 6, 26, -2, 6, 6, 14, -2, -26, -2, -10, -10, 6, -2, -18, 2, -10, 6, -10, -2, 14, 6, 14, 6, 6, -2, 62, -2, 6, -10, 2, 6, -26, -2, -10, 6, -26, -2, -50, -2, 6, -10, -10, 6, -26, -2, -18, 2, 6, -2, 62, 6, 6, 6, 14, -2, 62, 6, -10, 6, 6, 6
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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a(1) = 1; a(n) = -2 * Sum_{d|n, d < n} a(d). - Ilya Gutkovskiy, Feb 23 2020
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PROG
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(PARI)
A050328(n) = if(1==n, n, sumdiv(n, d, if((d<n && issquarefree(n/d)), A050328(d), 0)));
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CROSSREFS
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KEYWORD
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easy,sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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