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A125197
Numbers such that pre- and post-concatenating 7, 13 and 31 results in six primes.
0
19, 3583, 11287, 62989, 63409, 89491, 93187, 104107, 106783, 155851, 178351, 1082467, 1219399, 1510207, 1566613, 1581469, 2246173, 2920693, 3081499, 3342277, 3523339, 3781849, 3820543, 4010161, 4824163, 4865827, 6091597
OFFSET
1,1
COMMENTS
It is conjectured that 7, 13 and 31 is the only triple with this property
EXAMPLE
3583 is a member as 3583, 73583, 35837, 123583, 358313, 313583, 358331 are all prime.
CROSSREFS
Sequence in context: A287938 A225602 A195756 * A375090 A238563 A281820
KEYWORD
hard,nonn,base
AUTHOR
Anton Vrba (antonvrba(AT)yahoo.com), Jan 13 2007
STATUS
approved