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A285379 Numbers k such that (47*10^k + 133)/9 is prime. 0
1, 3, 4, 6, 7, 9, 16, 45, 73, 75, 94, 217, 241, 294, 1074, 2133, 2379, 3504, 8241, 16218, 16387, 18135, 31771, 47331, 58456, 72696, 76672 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
For k>1, numbers such that the digit 5 followed by k-2 occurrences of the digit 2 followed by the digits 37 is prime (see Example section).
a(28) > 2*10^5.
LINKS
Makoto Kamada, Search for 52w37.
EXAMPLE
4 is in this sequence because (47*10^4 + 133)/9 = 52237 is prime.
Initial terms and primes associated:
a(1) = 1, 67;
a(2) = 3, 5237;
a(3) = 4, 52237;
a(4) = 6, 5222237;
a(5) = 7, 52222237; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(47*10^# + 133)/9] &]
CROSSREFS
Sequence in context: A094604 A108654 A131530 * A102093 A135215 A092494
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Apr 17 2017
STATUS
approved

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Last modified March 28 12:26 EDT 2024. Contains 371254 sequences. (Running on oeis4.)