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A275542
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The digits of the integers with the nonprimes removed.
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2
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2, 3, 5, 7, 2, 3, 5, 7, 2, 2, 2, 2, 2, 3, 2, 2, 5, 2, 2, 7, 2, 2, 3, 3, 3, 2, 3, 3, 3, 3, 5, 3, 3, 7, 3, 3, 2, 3, 5, 7, 5, 5, 5, 2, 5, 3, 5, 5, 5, 5, 5, 7, 5, 5, 2, 3, 5, 7, 7, 7, 7, 2, 7, 3, 7, 7, 5, 7, 7, 7, 7, 7, 2, 3, 5, 7, 2, 3, 5, 7
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OFFSET
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1,1
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COMMENTS
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Write the digits of the positive integers one by one: 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 0, 1, 1, 1, 2, 1, 3, 1, 4, 1, 5, 1, 6, 1, 7, 1, 8, 1, 9, 2, 0, 2, 1, etc. (this is A007376). Then from that sequence, remove the nonprimes, leaving a sequence that consists entirely of 2s, 3s, 5s and 7s.
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LINKS
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EXAMPLE
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From the single-digit numbers, we obviously get the first four terms of this sequence: 2, 3, 5, 7.
10 is composite and neither of its digits is a single-digit prime, so it contributes nothing to this sequence.
11 is prime but its digits consist of two 1s, so like 10 it also contributes nothing to the sequence.
12 is composite, but its least significant digit is 2, which is a prime, and thus 12 contributes a 2 to the sequence.
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MATHEMATICA
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Flatten[Table[Select[IntegerDigits[n], PrimeQ], {n, 100}]] (* Alonso del Arte, Aug 01 2016 *)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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