A266963 Numbers n such that (2^(n+7)*5^(n+6)-1024877)/9 is prime (n > 0).

1, 27, 37, 42, 94, 117, 667, 1413, 1764, 4138, 8341, 9337, 10737, 16132, 17425

Offset

1,2

Comments

Numbers n such that '108347' (prime) appended to n times the digit 2 is prime.

a(n) mod 3 <= 1.

Links

Table of n, a(n) for n=1..15.

Example

1 appears because 2108347 ('2' prepended to '108347') is prime.

Mathematica

Select[ Range[2000], PrimeQ[(2^(#+7) * 5^(#+6) - 1024877) / 9] &] (*Or*)
Select[ Range[2000], PrimeQ[5*(2^(#+7) * 5^(#+5) - 204979) / 9 + 2] &]

Prog

(Magma) [n: n in [1..700] |IsPrime((2^(n+7)*5^(n+6)-1024877) div 9)]; // Vincenzo Librandi, Jan 13 2016
(PARI) is(n) = ispseudoprime((2^(n+7)*5^(n+6) - 1024877) / 9); \\ Altug Alkan, Jan 15 2016

Crossrefs

Sequence in context: A152053 A166649 A025145 * A180961 A278643 A069105

Adjacent sequences: A266960 A266961 A266962 * A266964 A266965 A266966

Keyword

nonn,base,more

Author

Mikk Heidemaa, Jan 07 2016

Status

approved