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A275783
Numbers n such that 10^n + 9^(n+1) is prime.
0
2, 3, 6, 11, 44, 64, 83, 123, 166, 381, 446, 1221, 1540, 3156, 5117, 5476, 6291, 6353, 13053, 15158, 23904, 78288, 82254, 91230
OFFSET
1,1
COMMENTS
a(25) > 10^5.
EXAMPLE
3 is a member since 10^3 + 9^4 = 1000 + 6561 = 7561 which is a prime number.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[10^# + 9^(# + 1)] &]
PROG
(PARI) is(n)=ispseudoprime(10^n+9^(n+1)) \\ Charles R Greathouse IV, Jun 13 2017
KEYWORD
nonn,more
AUTHOR
Robert Price, Aug 08 2016
STATUS
approved