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A274331
Numbers k such that (148*10^k - 1)/3 is prime.
0
2, 3, 4, 5, 9, 27, 35, 44, 88, 104, 205, 290, 302, 381, 400, 686, 917, 1150, 2278, 2757, 3220, 3316, 7469, 9535, 21442, 46409, 103718, 123688, 147139
OFFSET
1,1
Numbers k such that the digits 49 followed by k occurrences of the digit 3 is prime (see Example section).
a(30) > 2*10^5.
EXAMPLE
3 is in this sequence because (148*10^3-1)/3 = 233329 is prime.
Initial terms and associated primes:
a(1) = 2, 4933;
a(2) = 3, 49333;
a(3) = 4, 493333;
a(4) = 5, 4933333;
a(5) = 9, 49333333333, etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(148*10^# - 1)/3] &]
PROG
(PARI) is(n)=ispseudoprime((148*10^n - 1)/3) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A355374 A357601 A065885 * A177064 A092233 A115895
KEYWORD
nonn,more
AUTHOR
Robert Price, Jun 18 2016
EXTENSIONS
a(27)-a(29) from Robert Price, Mar 18 2020
STATUS
approved

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Last modified September 20 10:59 EDT 2024. Contains 376068 sequences. (Running on oeis4.)