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A273002
Numbers k such that 16*10^k + 1 is prime.
1
0, 2, 3, 4, 18, 21, 36, 58, 68, 78, 84, 94, 150, 178, 190, 591, 686, 812, 840, 2308, 2530, 2884, 4311, 6134, 7695, 8004, 8109, 9777, 15570, 17505
OFFSET
1,2
COMMENTS
For k > 1, numbers k such that the digits 16 followed by k-1 occurrences of the digit 0 followed by the digit 1 is prime (see Example section).
a(31) > 10^5.
EXAMPLE
4 is in this sequence because 16*10^4+1 = 160001 is prime.
Initial terms and associated primes:
a(1) = 0, 17;
a(2) = 2, 1601;
a(3) = 3, 16001;
a(4) = 4, 160001;
a(5) = 18, 16000000000000000001. etc.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[16*10^#+1] &]
PROG
(PARI) is(n)=ispseudoprime(16*10^n+1) \\ Charles R Greathouse IV, Jun 13 2017
KEYWORD
nonn,more
AUTHOR
Robert Price, May 12 2016
STATUS
approved