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A290432 Numbers k such that 9*10^k + 59 is prime. 0
1, 3, 4, 6, 7, 12, 17, 28, 46, 75, 105, 309, 351, 460, 774, 785, 2206, 5739, 12427, 14501, 17950, 68331 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For k > 1, numbers such that the digit 9 followed by k-2 occurrences of the digit 0 followed by the digits 59 is prime (see Example section).

a(23) > 10^5.

LINKS

Table of n, a(n) for n=1..22.

Makoto Kamada, Factorization of near-repdigit-related numbers.

Makoto Kamada, Search for 90w59

EXAMPLE

3 is in this sequence because 9*10^3 + 59 = 9059 is prime.

Initial terms and primes associated:

a(1) = 1, 149;

a(2) = 3, 9059;

a(3) = 4, 90059;

a(4) = 6, 9000059;

a(5) = 7, 90000059; etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[9*10^# + 59] &]

CROSSREFS

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Sequence in context: A211384 A281828 A002982 * A276783 A288731 A093707

Adjacent sequences:  A290429 A290430 A290431 * A290433 A290434 A290435

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Oct 06 2017

STATUS

approved

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Last modified August 15 20:49 EDT 2018. Contains 313779 sequences. (Running on oeis4.)