

A275680


Nonprime integers that become prime when concatenated with the next digit.


1



1, 9, 70, 10, 12, 72, 74, 30, 75, 14, 90, 76, 15, 16, 33, 18, 100, 91, 92, 93, 77, 34, 78, 700, 102, 104, 94, 105, 106, 35, 36, 702, 703, 95, 38, 39, 704, 300, 108, 705, 706, 96, 707, 98, 301, 99, 110, 302, 303, 710, 304, 111, 712, 112, 306, 115, 116, 308, 310, 900, 117, 118, 119, 312, 120, 121, 316, 318, 122, 319, 123, 124, 901, 125, 902, 904
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OFFSET

1,2


COMMENTS

The sequence is started with a(1) = 1 and always extended with the smallest integer not yet present that does not lead to a contradiction.


LINKS

JeanMarc Falcoz, Table of n, a(n) for n = 1..10001


EXAMPLE

1 is not prime but 19 is [1,9].
9 is not prime but 97 is [9,7(0)].
70 is not prime but 701 is [70,1(0)].
10 is not prime but 101 is [10,1(2)].
12 is not prime but 127 is [12,7(2)].
72 is not prime but 727 is [72,7(4)].
74 is not prime but 743 is [74,3(0)].
30 is not prime but 307 is [30,7(5)].
75 is not prime but 751 is [75,1(4)].
14 is not prime but 149 is [14,9(0)].
...


CROSSREFS

Sequence in context: A152273 A217452 A193706 * A167534 A110202 A110201
Adjacent sequences: A275677 A275678 A275679 * A275681 A275682 A275683


KEYWORD

nonn,base


AUTHOR

Eric Angelini and JeanMarc Falcoz, Aug 05 2016


STATUS

approved



