

A111475


a(1) = 7, a(n) = least k such that concatenation of n copies of k with all previous concatenation gives a prime.


5



7, 3, 1, 1, 1, 1, 129, 123, 97, 559, 781, 459, 253, 183, 413, 417, 657, 77, 437, 1439, 667, 1281, 3379, 979, 2763, 1953, 103, 10083, 5103, 291, 1311, 2199, 1159, 501, 5931, 483, 6171, 16301, 1781, 1229, 9519, 607, 5113, 2641, 1441, 8511, 9023, 363, 4001, 15261
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..50.


EXAMPLE

7,733,733111,... are all prime.
733111 = one copy of 7, two copies of 3, three copies of 1.


CROSSREFS

Cf. A111471, A111472, A111473, A111474, A111476.
Sequence in context: A334060 A083803 A136595 * A222581 A010139 A078075
Adjacent sequences: A111472 A111473 A111474 * A111476 A111477 A111478


KEYWORD

base,hard,nonn


AUTHOR

Amarnath Murthy, Aug 05 2005


EXTENSIONS

Extended by Max Alekseyev, May 19 2009


STATUS

approved



