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A103178
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Number of divisors of the decimal concatenation of the first n primes.
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0
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2, 2, 4, 2, 8, 8, 4, 8, 8, 8, 32, 24, 8, 16, 8, 16, 16, 16, 4, 8, 8, 16, 8, 24, 16, 64, 4, 32, 8, 128, 32, 32, 128, 128, 192, 16, 16, 64, 16, 768, 8, 48, 256, 128
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Catcon News.
Patrick De Geest, Repeated Factorisation of Concatenated Primefactors of the Composite Numbers
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EXAMPLE
| The number of divisors of 2 is 2, so the first term is 2.
The number of divisors of 23 is 2, so the second term is 2.
The number of divisors of 235 is 4, so the third term is 4.
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MATHEMATICA
| Table[DivisorSigma[0, FromDigits[Flatten[Table[IntegerDigits[Prime[j]], {j, 1, n}], 1]]], {n, 1, 100}] (Labos)
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CROSSREFS
| a(n)=A000005[A019518(n)]. Cf. A074809.
Sequence in context: A084540 A113416 A131999 * A173300 A181236 A087909
Adjacent sequences: A103175 A103176 A103177 * A103179 A103180 A103181
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KEYWORD
| nonn,base
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Mar 17 2005
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EXTENSIONS
| More terms from Labos E. (labos(AT)ana.sote.hu), Mar 18 2005
Extended and edited by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Apr 25 2010
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