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A113574
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Least number in which the r-th digit from the most significant side is prime if r is prime else it is composite, for r =1 the digit is 1.
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0
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1, 12, 122, 1224, 12242, 122424, 1224242, 12242424, 122424244, 1224242444, 12242424442, 122424244424, 1224242444242, 12242424442424, 122424244424244, 1224242444242444, 12242424442424442, 122424244424244424
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(n+1) = a(n) concatenated with 2 if n+1 is prime, else a(n+1) = a(n) concatenated with 4.
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CROSSREFS
| Sequence in context: A134584 A090843 A132927 * A199592 A078189 A167208
Adjacent sequences: A113571 A113572 A113573 * A113575 A113576 A113577
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KEYWORD
| base,easy,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Nov 06 2005
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EXTENSIONS
| Corrected and extended by Alvin H. Belt (AlvinBelt(AT)msn.com), Mar 24 2008
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