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A176942
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Champernowne primes.
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6
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OFFSET
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1,1
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COMMENTS
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Primes formed from an initial portion 1234... of the infinite string 12345678910111213... of the concatenation of all positive integers (decimal digits of the Champernowne constant).
The next terms are too big to display:
a(4) = 123456789...1121131141 (235 digits)
a(5) = 123456789...6896997097 (2804 digits)
a(6) = 12345...13611362136313 (4347 digits)
a(7) = 123456789...9709971097 (37735 digis)
a(8) has more than 37800 digits. (End)
a(8) has more than 140000 digits. - Tyler Busby, Feb 12 2023
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REFERENCES
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R. W. Stephan, Factors and primes in two Smarandache sequences.
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LINKS
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MATHEMATICA
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With[{no=500}, FromDigits/@Select[Table[Take[Flatten[IntegerDigits/@Range[no]], n], {n, no}], PrimeQ[FromDigits[#]]&]] (* Harvey P. Dale, Feb 06 2011 *)
Select[Table[Floor[N[ChampernowneNumber[10], n]*10^n], {n, 24}], PrimeQ] (* Arkadiusz Wesolowski, May 10 2012 *)
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CROSSREFS
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Cf. A007376 (infinite Barbier word = almost-natural numbers: write n in base 10 and juxtapose digits).
Cf. A033307 (decimal expansion of Champernowne constant).
Cf. A071620 (number of digits in the n-th Champernowne prime).
See A265043 for where to end the string of numbers that are being concatenated in order to get the n-th prime.
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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