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A324279
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Lexicographically earliest sequence of different terms starting with a(1) = 1 such that the n-th digit of the sequence, placed in front of a(n) and then concatenated, produces a prime.
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4
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1, 13, 7, 3, 11, 9, 27, 19, 23, 33, 31, 29, 39, 17, 37, 47, 49, 51, 41, 53, 59, 67, 57, 43, 73, 61, 21, 69, 63, 71, 77, 79, 87, 81, 93, 83, 99, 91, 113, 97, 119, 121, 111, 89, 127, 137, 131, 117, 129, 123, 133, 151, 143, 163, 159, 153, 177, 187, 193, 157, 147, 211, 161, 171, 173, 167, 179, 169, 181, 199, 221, 213, 217, 223, 191, 227
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OFFSET
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1,2
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COMMENTS
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No digit 0 is admitted in a(n) in order to avoid leading zeroes after the concatenation.
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LINKS
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Jean-Marc Falcoz, Table of n, a(n) for n = 1..10002
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EXAMPLE
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The 1st digit of the sequence (1) concatenated to the 1st term = 11 (prime);
the 2nd digit of the sequence (1) concatenated to the 2nd term = 113 (prime);
the 3rd digit of the sequence (3) concatenated to the 3rd term = 37 (prime);
the 4th digit of the sequence (7) concatenated to the 4th term = 73 (prime);
the 5th digit of the sequence (3) concatenated to the 5th term = 311 (prime);
the 6th digit of the sequence (1) concatenated to the 6th term = 19 (prime);
the 7th digit of the sequence (1) concatenated to the 7th term = 127 (prime);
the 8th digit of the sequence (9) concatenated to the 8th term = 919 (prime);
the 9th digit of the sequence (2) concatenated to the 9th term = 223 (prime);
etc.
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CROSSREFS
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Cf. A306321, A306311, A324280, A324281 and A324282 where the same idea is used.
Sequence in context: A078438 A225954 A133723 * A222464 A095389 A217518
Adjacent sequences: A324276 A324277 A324278 * A324280 A324281 A324282
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KEYWORD
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base,nonn
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AUTHOR
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Eric Angelini and Jean-Marc Falcoz, Feb 20 2019
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STATUS
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approved
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