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A165449
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Write the prime numbers in a string: 2357111317192329... (cf. A033308). The sequence gives the first position in the string for natural numbers appearing in the string, and -1 for the others natural numbers.
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2
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5, 1, 2, 21, 3, 31, 4, 41, 12, 47, 5, 62, 7, 22, 77, 32, 9, 95, 11, 589, 110, 113, 1, 128, 131, 137, 63, 149, 15, 158, 8, 14, 123, 24, 2, 188, 19, 42, 72, 206, 21, 215, 23, 227, 233, 236, 25, 248, 75, 257, 78, 263, 27, 269, 275, 278, 3, 290, 29, 299, 31, 829
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internal format)
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OFFSET
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1,1
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LINKS
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Nathaniel Johnston, Table of n, a(n) for n = 1..5000
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EXAMPLE
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The first occurence of "111" in the string is 5, so A(111)=5.
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MAPLE
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with(StringTools): s:="": for n from 1 to 300 do s:=cat(s, convert(ithprime(n), string)): od: seq(Search(convert(n, string), s), n=1..62); # Nathaniel Johnston, May 26 2011
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CROSSREFS
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Cf. A031297.
Sequence in context: A088781 A085608 A197080 * A019114 A201526 A091384
Adjacent sequences: A165446 A165447 A165448 * A165450 A165451 A165452
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KEYWORD
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easy,base,nonn
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AUTHOR
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Remy Sigrist (remysigrist(AT)free.fr), Sep 20 2009
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STATUS
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approved
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