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A297417
Numbers k such that (14*10^k + 37)/3 is prime.
0
0, 1, 2, 3, 4, 6, 8, 10, 14, 36, 41, 213, 229, 555, 569, 2295, 3108, 5944, 7370, 17615, 45894, 141853, 154773, 184150
OFFSET
1,3
COMMENTS
For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 6 followed by the digits 79 is prime (see Example section).
a(25) > 2*10^5.
EXAMPLE
2 is in this sequence because (14*10^2 + 37)/3 = 479 is prime.
Initial terms and associated primes:
a(1) = 0, 17;
a(2) = 1, 59;
a(3) = 2, 479;
a(4) = 3, 4679;
a(5) = 4, 46679; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(14*10^# + 37)/3] &]
PROG
(PARI) isok(k) = isprime((14*10^k + 37)/3); \\ Michel Marcus, Dec 30 2017
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Dec 29 2017
EXTENSIONS
a(22)-a(24) from Robert Price, Dec 05 2018
STATUS
approved