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A293537 Numbers k such that (88*10^k - 1)/3 is prime. 0
0, 1, 3, 6, 9, 121, 153, 172, 378, 496, 841, 1594, 1924, 2692, 4617, 5148, 12891, 24259, 24684, 27690, 68256, 93760 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Numbers such that the digits 29 followed by k occurrences of the digit 3 is prime (see Example section).

a(23) > 10^5.

LINKS

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

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

Makoto Kamada, Search for 293w

EXAMPLE

3 is in this sequence because (88*10^3 - 1)/3 = 29333 is prime.

Initial terms and primes associated:

a(1) = 0, 29;

a(2) = 1, 293;

a(3) = 3, 29333;

a(4) = 6, 29333333;

a(5) = 9, 29333333333; etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(88*10^# - 1)/3] &]

CROSSREFS

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

Sequence in context: A196156 A103978 A289064 * A073910 A115251 A057241

Adjacent sequences:  A293534 A293535 A293536 * A293538 A293539 A293540

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Oct 11 2017

STATUS

approved

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Last modified March 22 12:39 EDT 2019. Contains 321421 sequences. (Running on oeis4.)