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A273063 Numbers k such that (112*10^k + 17)/3 is prime. 0
0, 1, 2, 3, 4, 8, 44, 53, 79, 89, 95, 120, 224, 259, 290, 488, 725, 821, 1815, 3096, 3100, 3404, 5909, 8054, 11879, 17298, 25588, 41516, 127324, 191900 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

For k>0, numbers k such that the digits 37 followed by k-1 occurrences of the digit 3 followed by the digit 9 is prime (see Example section).

a(31) > 2*10^5.

LINKS

Table of n, a(n) for n=1..30.

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

Makoto Kamada, Search for 373w9.

EXAMPLE

3 is in this sequence because (112*10^3+17)/3 = 37339 is prime.

Initial terms and primes associated:

a(1) = 0, 43;

a(2) = 1, 379:

a(3) = 2, 3739;

a(4) = 3, 37339;

a(5) = 4, 373339, etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(112*10^# + 17)/3] &]

PROG

(PARI) is(n)=ispseudoprime((112*10^n + 17)/3) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

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

Sequence in context: A100997 A128657 A105421 * A217353 A258194 A033554

Adjacent sequences:  A273060 A273061 A273062 * A273064 A273065 A273066

KEYWORD

nonn,more

AUTHOR

Robert Price, May 14 2016

EXTENSIONS

a(29)-a(30) from Robert Price, Mar 05 2020

STATUS

approved

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Last modified June 20 08:43 EDT 2021. Contains 345162 sequences. (Running on oeis4.)