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A295628 Numbers k such that (404*10^k - 53)/9 is prime. 0
1, 2, 4, 8, 22, 37, 38, 64, 80, 92, 104, 136, 164, 172, 349, 1492, 2551, 16375, 58087, 59149 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
For k > 1, numbers such that the digits 44 followed by k-1 occurrences of the digit 8 followed by the digit 3 is prime (see Example section).
a(21) > 2*10^5.
LINKS
Makoto Kamada, Search for 448w3.
EXAMPLE
2 is in this sequence because (404*10^2 - 53)/9 = 4483 is prime.
Initial terms and primes associated:
a(1) = 1, 443;
a(2) = 2, 4483;
a(3) = 4, 448883;
a(4) = 8, 4488888883;
a(5) = 22, 448888888888888888888883; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(404*10^# - 53)/9] &]
CROSSREFS
Sequence in context: A192149 A115778 A333016 * A027713 A155765 A217975
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Nov 24 2017
STATUS
approved

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Last modified March 28 16:28 EDT 2024. Contains 371254 sequences. (Running on oeis4.)