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A073255
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Sum of divisors of n-th composite number.
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11
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7, 12, 15, 13, 18, 28, 24, 24, 31, 39, 42, 32, 36, 60, 31, 42, 40, 56, 72, 63, 48, 54, 48, 91, 60, 56, 90, 96, 84, 78, 72, 124, 57, 93, 72, 98, 120, 72, 120, 80, 90, 168, 96, 104, 127, 84, 144, 126, 96, 144, 195, 114, 124, 140, 96, 168, 186, 121, 126, 224, 108, 132
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n)=A000203[A002808(n)]
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EXAMPLE
| First composite is 4, sigma[4]=1+2+4=7=a(1).
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MATHEMATICA
| c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] Table[DivisorSigma[1, c[w]], {w, 1, 128}]
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CROSSREFS
| Cf. A000203, A002808, A035004.
Sequence in context: A153245 A062730 * A162194 A145310 A177988 A072834
Adjacent sequences: A073252 A073253 A073254 * A073256 A073257 A073258
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Jul 22 2002
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