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A294678 Numbers k such that (26*10^k - 167)/3 is prime. 0
1, 2, 27, 38, 51, 122, 200, 408, 422, 680, 732, 1128, 2448, 3237, 8964, 11208, 14970, 15769, 17411, 27813, 46521, 101537, 164643, 167861 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For k>1, numbers such that the digit 8 followed by k-2 occurrences of the digit 6 followed by the digits 11 is prime (see Example section).

a(25) > 2*10^5.

LINKS

Table of n, a(n) for n=1..24.

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

Makoto Kamada, Search for 86w11.

EXAMPLE

2 is in this sequence because (26*10^2 - 167)/3 = 811 is prime.

Initial terms and primes associated:

a(1) = 1, 31;

a(2) = 2, 811;

a(3) = 27, 8666666666666666666666666611;

a(4) = 38, 866666666666666666666666666666666666611;

a(5) = 51, 8666666666666666666666666666666666666666666666666611; etc.

MAPLE

P:=proc(k) if isprime((26*10^k - 167)/3) then k; fi; end: seq(P(i), i=1..46521); # Paolo P. Lava, Nov 07 2017

MATHEMATICA

Select[Range[1, 100000], PrimeQ[(26*10^# - 167)/3] &]

CROSSREFS

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

Sequence in context: A226670 A277542 A273844 * A206585 A046735 A038625

Adjacent sequences:  A294675 A294676 A294677 * A294679 A294680 A294681

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Nov 06 2017

EXTENSIONS

a(22)-a(24) from Robert Price, Oct 08 2019

STATUS

approved

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Last modified May 13 19:36 EDT 2021. Contains 343868 sequences. (Running on oeis4.)