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A290877
Numbers k such that 3*10^k + 59 is prime.
0
1, 2, 4, 7, 18, 19, 22, 26, 36, 46, 49, 64, 82, 121, 1204, 1716, 2359, 4541, 7194, 8095, 14857, 18596, 27648, 37066, 109861, 171391
OFFSET
1,2
COMMENTS
For k > 1, numbers k such that the digit 3 followed by k-2 occurrences of the digit 0 followed by the digits 59 is prime (see Example section).
a(27) > 2*10^5.
EXAMPLE
4 is in this sequence because 3*10^4 + 59 = 30059 is prime.
Initial terms and associated primes:
a(1) = 1, 89;
a(2) = 2, 359;
a(3) = 4, 30059;
a(4) = 7; 30000059;
a(5) = 18, 3000000000000000059; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[3*10^# + 59] &]
PROG
(PARI) isok(k) = ispseudoprime(3*10^k + 59) \\ Altug Alkan, Aug 13 2017
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Aug 13 2017
EXTENSIONS
a(25)-a(26) from Robert Price, Aug 25 2018
STATUS
approved