A269797 - OEIS

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A269797

Numbers k such that (29*10^k + 91)/3 is prime.

1, 2, 3, 4, 8, 11, 18, 27, 39, 54, 55, 65, 75, 83, 111, 164, 189, 191, 204, 252, 322, 371, 449, 646, 678, 754, 1641, 5210, 7787, 11691, 13682, 15994, 22356, 29203, 35756, 57834, 64027, 72985, 74276, 104071, 219124

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OFFSET

1,2

COMMENTS

For k > 1, numbers k such that digit 9 followed by k-2 occurrences of digit 6 followed by the digits 97 is prime (see Example section).

a(42) > 3*10^5.

LINKS

Table of n, a(n) for n=1..41.

Makoto Kamada, Search for 96w97.

EXAMPLE

6 is in this sequence because (266*10^n+1)/3 = 88666667 is prime.

Initial terms and associated primes:

a(1) = 1, 127,

a(2) = 2, 997,

a(3) = 3, 9697,

a(4) = 4, 96697,

a(5) = 8, 966666697,

a(6) = 11, 966666666697,

a(7) = 18, 9666666666666666697,

a(8) = 27, 9666666666666666666666666697,

a(9) = 39, 9666666666666666666666666666666666666697, etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(29*10^# + 91)/3] &]

PROG

(PARI) isok(n) = isprime((29*10^n + 91)/3); \\ Michel Marcus, Mar 05 2016

CROSSREFS

Cf. A056654, A268448, A269303.

Sequence in context: A015935 A135909 A046812 * A280195 A286224 A361313

Adjacent sequences: A269794 A269795 A269796 * A269798 A269799 A269800

KEYWORD

nonn,more

AUTHOR

Robert Price, Mar 05 2016

EXTENSIONS

a(40) from Robert Price, Apr 12 2020

a(41) from Robert Price, May 31 2023

STATUS

approved