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A276046 Numbers n such that (26*10^n - 23)/3 is prime. 0
1, 2, 10, 16, 78, 97, 125, 138, 192, 242, 290, 373, 408, 467, 583, 892, 899, 1709, 1944, 2154, 3618, 5225, 8974, 9377, 12504, 20042, 49106, 63073, 92152 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For n>1, numbers such that the digit 8 followed by n-2 occurrences of the digit 6 followed by the digits 59 is prime (see Example section).

a(30) > 10^5.

LINKS

Table of n, a(n) for n=1..29.

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

Makoto Kamada, Search for 86w59.

EXAMPLE

2 is in this sequence because (26*10^2 - 23)/3 = 859 is prime.

Initial terms and primes associated:

a(1) = 1, 79;

a(2) = 2, 859;

a(3) = 10, 86666666659;

a(4) = 16, 86666666666666659, etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(26*10^# - 23)/3] &]

PROG

(PARI) is(n)=ispseudoprime((26*10^n-23)/3) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

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

Sequence in context: A046036 A131474 A249153 * A268481 A009387 A305093

Adjacent sequences:  A276043 A276044 A276045 * A276047 A276048 A276049

KEYWORD

nonn,more

AUTHOR

Robert Price, Aug 17 2016

STATUS

approved

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Last modified June 16 12:38 EDT 2019. Contains 324152 sequences. (Running on oeis4.)