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A290218 Numbers k such that (29*10^k + 67)/3 is prime. 0
3, 6, 8, 10, 16, 80, 105, 123, 130, 159, 160, 300, 597, 1653, 3576, 4535, 6164, 8601, 24203, 24636, 165796, 171275 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For k>1, numbers such that the digit 9 followed by k-2 occurrences of the digit 6 followed by the digits 89 is prime (see Example section).

a(23) > 2*10^5.

LINKS

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

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

Makoto Kamada, Search for 96w89.

EXAMPLE

3 is in this sequence because (29*10^3 + 67)/3 = 9689 is prime.

Initial terms and primes associated:

a(1) = 3, 9689;

a(2) = 6, 9666689;

a(3) = 8, 966666689;

a(4) = 10, 96666666689;

a(5) = 16, 96666666666666689; etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(29*10^# + 67)/3] &]

CROSSREFS

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

Sequence in context: A343409 A043549 A228707 * A310135 A124051 A294086

Adjacent sequences:  A290215 A290216 A290217 * A290219 A290220 A290221

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Oct 09 2017

EXTENSIONS

a(21)-a(22) from Robert Price, Dec 18 2019

STATUS

approved

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Last modified June 12 14:15 EDT 2021. Contains 344956 sequences. (Running on oeis4.)