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URL: https://oeis.org/A296053

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A296053
Numbers k such that (46*10^k + 683)/9 is prime.
0
1, 2, 11, 17, 35, 56, 91, 187, 199, 224, 625, 655, 665, 959, 1457, 1501, 1970, 4478, 12514, 45820, 68698, 113969, 117902, 182896, 192841
OFFSET
1,2
COMMENTS
For k > 1, numbers k such that the digit 5 followed by k-2 occurrences of the digit 1 followed by the digits 87 is prime (see Example section).
a(26) > 2*10^5.
EXAMPLE
2 is in this sequence because (46*10^2 + 683)/9 = 587 is prime.
Initial terms and associated primes:
a(1) = 1, 127;
a(2) = 2, 587;
a(3) = 11, 511111111187;
a(4) = 17, 511111111111111187;
a(5) = 35, 511111111111111111111111111111111187; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(46*10^# + 683)/9] &]
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Dec 03 2017
EXTENSIONS
a(22)-a(25) from Robert Price, Mar 24 2019
STATUS
approved