

A282139


Numbers k such that (22*10^k  19)/3 is prime.


0



1, 2, 4, 6, 14, 15, 24, 48, 78, 112, 122, 334, 504, 872, 914, 1230, 1506, 2442, 4095, 5022, 10615, 11460, 18303, 33675, 47701, 55592, 84159
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OFFSET

1,2


COMMENTS

For k > 1, numbers such that the digit 7 followed by k  2 occurrences of the digit 3 followed by the digits 27 is prime (see Example section).
a(28) > 10^5.


LINKS

Table of n, a(n) for n=1..27.
Makoto Kamada, Factorization of nearrepdigitrelated numbers.
Makoto Kamada, Search for 73w27.


EXAMPLE

4 is in this sequence because (22*10^4  19)/3 = 73327 is prime.
Initial terms and primes associated:
a(1) = 1, 67;
a(2) = 2, 727;
a(3) = 4, 73327;
a(4) = 6, 7333327;
a(5) = 14, 733333333333327; etc.


MATHEMATICA

Select[Range[0, 100000], PrimeQ[(22 * 10^#  19)/3] &]


CROSSREFS

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
Sequence in context: A105543 A295618 A027712 * A138307 A124693 A095698
Adjacent sequences: A282136 A282137 A282138 * A282140 A282141 A282142


KEYWORD

nonn,more,hard


AUTHOR

Robert Price, Feb 06 2017


STATUS

approved



