A095304 Smallest prime of the form k^n-2.

2, 2, 727, 79, 241, 727, 823541, 5764799, 19681, 16679880978199, 31381059607, 13841287199, 42052983462257057, 6103515623, 4747561509941, 28644003124274380508351359, 98526125335693359373, 136753052840548005895349735207879, 22168378200531005859373

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Example

a(7)=7^7-2=823541 is prime whereas 3^7-2=2185 and 5^7-2=78123 are composite.

Mathematica

Table[k = 2; While[p = k^n - 2; ! PrimeQ[p], k++]; p, {n, 20}] (* T. D. Noe, Apr 03 2012 *)

Crossrefs

Cf. A095303 (smallest k such that k^n-2 is prime), A087576 (smallest k such that k^n+2 is prime), A095302 (corresponding primes).

Sequence in context: A371203 A013556 A093596 * A111819 A287764 A260753

Adjacent sequences: A095301 A095302 A095303 * A095305 A095306 A095307

Keyword

nonn

Author

Hugo Pfoertner, Jun 01 2004

Extensions

a(2) corrected by Zak Seidov, Apr 03 2012

Status

approved