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A285632
Numbers k such that 6*10^k + 17 is prime.
0
0, 2, 4, 8, 40, 116, 234, 258, 532, 1048, 1062, 1590, 2594, 3286, 4036, 6232, 6700, 7800, 12002, 13296, 23124, 29338, 181306
OFFSET
1,2
COMMENTS
For k > 1, numbers k such that the digit 6 followed by k-2 occurrences of the digit 0 followed by the digits 17 is prime (see Example section).
a(24) > 2*10^5.
If k is odd then 6*10^k + 17 is divisible by 11. - David Radcliffe, Sep 04 2018
EXAMPLE
4 is in this sequence because 6*10^4 + 17 = 60017 is prime.
Initial terms and associated primes:
a(1) = 0, 23;
a(2) = 2, 617;
a(3) = 4, 60017;
a(4) = 8, 600000017;
a(5) = 40, 60000000000000000000000000000000000000017; etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ{6*10^# + 17] &]
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Apr 23 2017
EXTENSIONS
a(23) from Robert Price, Apr 07 2019
STATUS
approved