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Search: id:A155032
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| A155032 |
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Primes n such that concatenation of pi(n) and n is prime, with pi being the prime counting function. |
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+0
2
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| 3, 59, 83, 179, 283, 353, 431, 709, 1433, 2269, 2381, 3559, 3593, 4153, 5503, 6899, 7109, 7351, 7649, 8513, 11909, 13297, 14107, 14437, 14591, 16073, 16127, 16451, 16901, 17117, 17539, 17987, 18149, 19777, 20759, 21317, 22027, 24439, 25357, 26783, 27437, 29269, 30253, 32299, 34057, 34259, 34421, 34543, 35617, 36307, 37049
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OFFSET
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1,1
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EXAMPLE
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Since 3 is the second prime number and the concatenation of 2 and 3 gives 23, which is prime, 3 is in the sequence. Since 59 is the seventeenth prime and the concatenation of 17 and 59 gives 1759, another prime, 59 is also in the sequence.
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MATHEMATICA
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(*First run the program given for A154963*) Prime[A154963]
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CROSSREFS
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pi(a(n)) = A154963.
Sequence in context: A100611 A139882 A139874 this_sequence A107212 A002148 A057175
Adjacent sequences: A155029 A155030 A155031 this_sequence A155033 A155034 A155035
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KEYWORD
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nonn,base
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AUTHOR
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Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jan 19 2009
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EXTENSIONS
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Edited and extended beyond a(3) by Alonso Delarte (alonso.delarte(AT)gmail.com), Jan 20 2009, with thanks to Klaus Brockhaus's edit of A154963
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