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A176942 Champernowne primes. 6
1234567891, 12345678910111, 123456789101112131415161 (list; graph; refs; listen; history; text; internal format)
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).
From Eric W. Weisstein, Jul 15 2013: (Start)
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
R. W. Stephan, Factors and primes in two Smarandache sequences.
Eric W. Weisstein, Table of n, a(n) for n = 1..7 (an a-file)
Eric Weisstein's World of Mathematics, Champernowne Constant
Eric Weisstein's World of Mathematics, Constant Primes
Eric Weisstein's World of Mathematics, Integer Sequence Primes
Eric Weisstein's World of Mathematics, Smarandache Prime
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 *)
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.
Sequence in context: A235640 A104953 A225139 * A154769 A187565 A204606
Marco Ripà, Jan 27 2011

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Last modified June 8 14:02 EDT 2023. Contains 363165 sequences. (Running on oeis4.)