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A288654
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a(n) = (sigma(n)-n-1)*(3-omega(n)).
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2
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-3, 0, 0, 4, 0, 5, 0, 12, 6, 7, 0, 15, 0, 9, 8, 28, 0, 20, 0, 21, 10, 13, 0, 35, 10, 15, 24, 27, 0, 0, 0, 60, 14, 19, 12, 54, 0, 21, 16, 49, 0, 0, 0, 39, 32, 25, 0, 75, 14, 42, 20, 45, 0, 65, 16, 63, 22, 31, 0, 0, 0, 33, 40, 124, 18, 0, 0, 57, 26, 0, 0, 122
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OFFSET
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1,1
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COMMENTS
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If n is prime, then a(n) = 0. If n is semiprime, then a(n) = sopfr(n).
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LINKS
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MATHEMATICA
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Table[(DivisorSigma[1, n] - n - 1) (3 - PrimeNu[n]), {n, 100}]
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PROG
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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STATUS
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approved
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