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A293534 Numbers k such that 22*10^k + 3 is prime. 0
1, 2, 3, 6, 15, 18, 26, 51, 54, 68, 85, 242, 597, 2335, 3463, 4160, 5565, 8322, 11389, 43982, 70729, 127645, 151998 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
For k > 0, numbers k such that the digits 22 followed by k-1 occurrences of the digit 0 followed by the digit 3 is prime (see Example section).
a(24) > 2*10^5.
LINKS
Makoto Kamada, Search for 220w3.
EXAMPLE
2 is in this sequence because 22*10^2 + 3 = 2203 is prime.
Initial terms and associated primes:
a(1) = 1, 223;
a(2) = 2, 2203;
a(3) = 3, 22003;
a(4) = 6, 22000003;
a(5) = 15, 22000000000000003; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[22*10^# + 3] &]
PROG
(PARI) isok(k) = isprime(22*10^k + 3); \\ Altug Alkan, Oct 11 2017
CROSSREFS
Sequence in context: A335260 A090983 A198684 * A066653 A081945 A329745
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Oct 11 2017
EXTENSIONS
a(22)-a(23) from Robert Price, Jan 04 2020
STATUS
approved

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Last modified July 19 17:03 EDT 2024. Contains 374410 sequences. (Running on oeis4.)