

A324281


Lexicographically earliest sequence of different terms starting with a(1) = 2 such that the nth digit of the sequence, placed after a(n) and then concatenated, produces a composite number.


4



2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 14, 1, 16, 10, 17, 20, 13, 22, 15, 23, 18, 19, 21, 26, 24, 25, 27, 29, 28, 30, 32, 34, 31, 35, 33, 36, 37, 38, 39, 40, 41, 42, 43, 44, 47, 45, 46, 48, 49, 51, 50, 53, 52, 54, 55, 57, 56, 58, 59, 60, 62, 63, 61, 66, 65, 69, 64, 70, 67, 68, 71, 72, 73, 74, 75, 76, 78, 77, 79, 80, 81, 82, 83, 84, 85
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OFFSET

1,1


COMMENTS

The sequence is a permutation of the numbers > 0.


LINKS

JeanMarc Falcoz, Table of n, a(n) for n = 1..10009


EXAMPLE

The 1st digit of the sequence (2) concatenated to the 1st term = 22 (composite);
the 2nd digit of the sequence (3) concatenated to the 2nd term = 33 (composite);
the 3rd digit of the sequence (4) concatenated to the 3rd term = 44 (composite);
the 4th digit of the sequence (5) concatenated to the 4th term = 55 (composite);
the 5th digit of the sequence (6) concatenated to the 5th term = 66 (composite);
the 6th digit of the sequence (7) concatenated to the 6th term = 77 (composite);
the 7th digit of the sequence (8) concatenated to the 7th term = 88 (composite);
the 8th digit of the sequence (9) concatenated to the 8th term = 99 (composite);
the 9th digit of the sequence (1) concatenated to the 9th term = 111 (composite);
the 10th digit of the sequence (1) concatenated to the 10th term = 121 (composite);
the 11th digit of the sequence (1) concatenated to the 11th term = 141 (composite);
the 12th digit of the sequence (2) concatenated to the 12th term = 12 (composite);
the 13th digit of the sequence (1) concatenated to the 13th term = 161 (composite);
etc.


CROSSREFS

Cf. A306311, A306321, A324279, A324280 and A324282 where the same idea is used.
Sequence in context: A126969 A127274 A324280 * A129946 A099649 A330982
Adjacent sequences: A324278 A324279 A324280 * A324282 A324283 A324284


KEYWORD

base,nonn


AUTHOR

Eric Angelini and JeanMarc Falcoz, Feb 20 2019


STATUS

approved



