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Search: id:A103178
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| A103178 |
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a(n) is the number of divisors [A000005] of numbers which are obtained by concatenation of the first n primes. |
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+0
1
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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
(list; graph; listen)
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OFFSET
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0,1
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LINKS
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Catcon News.
Patrick De Geest, World!of Numbers
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EXAMPLE
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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
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Table[DivisorSigma[0, FromDigits[Flatten[Table[IntegerDigits[Prime[j]], {j, 1, n}], 1]]], {n, 1, 100}] (Labos)
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CROSSREFS
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a(n)=A000005[A019518(n)]. Cf. A074809.
Sequence in context: A084540 A113416 A131999 this_sequence A087909 A076078 A103314
Adjacent sequences: A103175 A103176 A103177 this_sequence A103179 A103180 A103181
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KEYWORD
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nonn,hard
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AUTHOR
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Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Mar 17 2005
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EXTENSIONS
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More terms from Labos E. (labos(AT)ana.sote.hu), Mar 18 2005
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