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A293535
Numbers k such that 2*10^k + 63 is prime.
0
1, 2, 3, 4, 5, 7, 9, 16, 35, 40, 71, 79, 82, 153, 167, 229, 652, 851, 1034, 1216, 1235, 1300, 7447, 26360, 30553, 36994, 47321, 95095, 141448, 179602
OFFSET
1,2
COMMENTS
For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 0 followed by the digits 63 is prime (see Example section).
a(31) > 2*10^5.
EXAMPLE
2 is in this sequence because 2*10^2 + 63 = 263 is prime.
Initial terms and associated primes:
a(1) = 1, 83;
a(2) = 2, 263;
a(3) = 3, 2063;
a(4) = 4, 20063;
a(5) = 5, 200063; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[2*10^# + 63] &]
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Oct 11 2017
EXTENSIONS
a(29)-a(30) from Robert Price, May 08 2018
STATUS
approved