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A281644
Numbers k such that 2*10^k + 41 is prime.
0
0, 1, 2, 5, 11, 13, 14, 36, 37, 41, 43, 49, 53, 138, 146, 269, 313, 428, 517, 860, 1297, 3185, 4477, 6737, 14204, 68744, 170767, 184723
OFFSET
1,3
COMMENTS
For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 0 followed by the digits 41 is prime (see Example section).
a(29) > 2*10^5.
EXAMPLE
2 is in this sequence because 2*10^2 + 41 = 241 is prime.
Initial terms and associated primes:
a(1) = 0, 43;
a(2) = 1, 61;
a(3) = 2, 24;
a(4) = 5, 200041;
a(5) = 11, 200000000041; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[2*10^# + 41 &]
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Jan 25 2017
EXTENSIONS
a(27)-a(28) from Robert Price, May 05 2018
STATUS
approved