A046867 Numbers n such that 10*11^n -1 is prime.

1, 3, 37, 119, 255, 355, 371, 497, 1759, 34863, 50719, 147709

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• hard

Comments

a(13) > 2*10^5. - Robert Price, Jan 19 2015

References

• R. K. Guy, Unsolved Problems in Theory of Numbers, Section A3.

Links

• H. C. Williams, The primality of certain integers of the form 2Ar^n - 1, Acta Arith. 39 (1981), 7-17.

Crossrefs

Cf. A003307, A002235, A046865, A079906, A046866, A001771, A005541, A056725, A079907.

Programs

Mathematica

Do[ If[ PrimeQ[10*11^n - 1], Print[n]], {n, 1, 2000}]

PARI

is(n)=isprime(10*11^n-1) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

One more term from Robert G. Wilson v, Jan 16 2003

a(10)-a(12) from Robert Price, Jan 19 2015