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A283684 Numbers k such that 3*10^k + 17 is prime. 0
1, 2, 5, 6, 13, 17, 24, 29, 38, 43, 59, 92, 350, 365, 679, 1016, 2958, 4434, 6306, 8819, 11687, 13484, 22189, 43034, 69354, 78146, 78631, 150182 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For k>1, numbers such that the digit 3 followed by k-2 occurrences of the digit 0 followed by the digits 17 is prime (see Example section).

a(29) > 2*10^5.

LINKS

Table of n, a(n) for n=1..28.

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

Makoto Kamada, Search for 30w17.

EXAMPLE

2 is in this sequence because 3*10^2 + 17 = 317 is prime.

Initial terms and primes associated:

a(1) = 1, 47;

a(2) = 2, 317;

a(3) = 5, 300017;

a(4) = 6, 3000017;

a(5) = 13, 30000000000017; etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[3*10^# + 17] &]

PROG

(PARI) isok(n) = isprime((3*10^n + 17)); \\ Indranil Ghosh, Mar 14 2017

CROSSREFS

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

Sequence in context: A098376 A028259 A327472 * A325285 A323348 A181314

Adjacent sequences:  A283681 A283682 A283683 * A283685 A283686 A283687

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Mar 14 2017

EXTENSIONS

a(28) from Robert Price, Jul 27 2018

STATUS

approved

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Last modified April 4 05:34 EDT 2020. Contains 333212 sequences. (Running on oeis4.)