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A162195
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Sum of proper divisors of n-th nonprime number A018252(n).
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2
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0, 3, 6, 7, 4, 8, 16, 10, 9, 15, 21, 22, 11, 14, 36, 6, 16, 13, 28, 42, 31, 15, 20, 13, 55, 22, 17, 50, 54, 40, 33, 26, 76, 8, 43, 21, 46, 66, 17, 64, 23, 32, 108, 34, 41, 63, 19, 78, 58, 27, 74, 123, 40, 49, 64, 19, 90, 106, 40, 44, 140, 23, 46, 33, 92, 144, 21, 76, 35, 50, 25
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OFFSET
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1,2
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COMMENTS
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The k-th positive integer of this sequence is equal to the sum of proper divisors of k-th composite number A002808(k).
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LINKS
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Table of n, a(n) for n=1..71.
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FORMULA
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a(n) = A001065(A018252(n)).
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MATHEMATICA
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NonPrime[n_Integer] := FixedPoint[n + PrimePi@# &, n + PrimePi@n]; f[n_] := Block[{m = NonPrime@n}, DivisorSigma[1, m] - m]; Array[f, 71] [From Robert G. Wilson v, Aug 17 2009]
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CROSSREFS
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Cf. A001065, A018252, A002808, A162194, A162196.
Sequence in context: A055102 A198457 A098990 * A117361 A165952 A156648
Adjacent sequences: A162192 A162193 A162194 * A162196 A162197 A162198
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KEYWORD
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easy,nonn
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AUTHOR
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Omar E. Pol, Jul 04 2009
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EXTENSIONS
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a(17) and further terms from Robert G. Wilson v, Aug 17 2009
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STATUS
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approved
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