A266962 Numbers n such that (2^(n+8) * 5^(n+5) - 409949) / 9 is prime (n > 0).

5, 65, 66, 168, 689, 1200, 1526, 1986, 7751

Offset

1,1

Comments

Numbers n such that '43339' appended to n times the digit 8 is prime.

a(n) mod 7 <= 5 (zero or prime <= 5).

Links

Table of n, a(n) for n=1..9.

Example

5 appears because 8888843339 ('8' concatenated 5 times and prepended to '43339') is prime.

Mathematica

Select[ Range[2000], PrimeQ[(2^(#+8)*5^(#+5) - 409949) / 9] &] (* Or *)
Select[ Range[2000], PrimeQ[2*(2^(#+7)*5^(#+5) - 204979) / 9 + 1] &]

Prog

(PARI) is(n) = ispseudoprime((2^(n+8)*5^(n+5) - 409949) / 9); \\ Altug Alkan, Jan 15 2016
(Magma) [n: n in [0..500] |IsPrime((2^(n+8)*5^(n+5)-409949) div 9)]; // Vincenzo Librandi, Jan 16 2016

Crossrefs

Cf. A266421.

Sequence in context: A351020 A238631 A220557 * A126955 A091105 A234335

Adjacent sequences: A266959 A266960 A266961 * A266963 A266964 A266965

Keyword

nonn,base,more

Author

Mikk Heidemaa, Jan 07 2016

Status

approved