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A111172
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Position of first occurrence of n in A039819.
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1
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1, 2, 4, 3, 63, 5, 6115, 7, 8, 13, 761401060, 11
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The sequence is well-defined because every integer occurs in the sequence A039819 at least once (see S. Colton, Theorem 5). a(11) is probably between 10^8 and 10^9, a(12)=11.
a(14) = 47. a(15) = 170. a(16) = 42. - Donovan Johnson, Apr 04 2011
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REFERENCES
| S. Colton, Refactorable Numbers - A Machine Invention, J. Integer Sequences, Vol. 2, 1999, #2.
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EXAMPLE
| a(6)=5 because the first 6 occurs in A039819 at position 5.
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MATHEMATICA
| c = 0; t = Table[0, {100}]; Do[d = DivisorSigma[0, n]; If[ Mod[n, d]==0, c++; If[d < 101 && t[[d]] == 0, t[[d]] = c; Print[{d, c, n}]]], {n, 10^9}]; t (* Robert G. Wilson v *)
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CROSSREFS
| Cf. A039819, A033950.
Sequence in context: A053124 A071970 A163089 * A173556 A198786 A176531
Adjacent sequences: A111169 A111170 A111171 * A111173 A111174 A111175
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KEYWORD
| nonn
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AUTHOR
| Franz Vrabec (franz.vrabec(AT)aon.at), Oct 21 2005
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EXTENSIONS
| a(11) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Apr 04 2011
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