

A295522


Numbers k such that (16*10^k + 107)/3 is prime.


0



0, 1, 2, 8, 18, 24, 96, 152, 204, 296, 566, 703, 1814, 4342, 4626, 5412, 6704, 6752, 7096, 27004, 37976, 173251
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OFFSET

1,3


COMMENTS

For k > 1, numbers such that the digit 5 followed by k2 occurrences of the digit 3 followed by the digits 69 is prime (see Example section).
a(23) > 2*10^5.


LINKS

Table of n, a(n) for n=1..22.
Makoto Kamada, Factorization of nearrepdigitrelated numbers.
Makoto Kamada, Search for 53w69


EXAMPLE

2 is in this sequence because (16*10^2 + 107)/3 = 569 is prime.
Initial terms and primes associated:
a(1) = 0, 41;
a(2) = 1, 89;
a(3) = 2, 569;
a(4) = 8, 533333369;
a(5) = 18, 5333333333333333369; etc.


MATHEMATICA

Select[Range[0, 100000], PrimeQ[(16*10^# + 107)/3] &]


CROSSREFS

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.
Sequence in context: A171613 A306394 A109136 * A065131 A192157 A268810
Adjacent sequences: A295519 A295520 A295521 * A295523 A295524 A295525


KEYWORD

nonn,more,hard


AUTHOR

Robert Price, Nov 28 2017


EXTENSIONS

a(22) from Robert Price, Mar 06 2019


STATUS

approved



