The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A250200 Least number k>1 such that (2n-1)^k - 2 is prime, or 0 if no such number exists. 3
 0, 2, 2, 2, 2, 4, 2, 2, 6, 2, 2, 24, 7, 2, 2, 3, 2, 2, 2, 4, 4, 2, 11, 2, 2, 8, 4, 2, 12, 4, 2, 2, 8, 3, 2, 2, 4, 2, 2, 38, 130, 4, 4, 4, 2, 3, 2, 4, 747, 3, 4, 2, 10, 2, 3, 17, 10, 13, 2, 2, 2, 6, 42, 2, 3, 2, 6, 2, 10, 2, 4, 4, 2, 16, 50, 3, 9, 2, 22, 25 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Robert Price, Table of n, a(n) for n = 1..143 MATHEMATICA lst = {0}; For[n = 2, n ≤ 143, n++, For[k = 2, k >= 1, k++, If[PrimeQ[(2*n - 1)^k - 2], AppendTo[lst, k]; Break[]]]]; lst lnk[n_]:=Module[{k=2, c=2n-1}, While[!PrimeQ[c^k-2], k++]; k]; Join[{0}, Array[ lnk, 80, 2]] (* Harvey P. Dale, Jul 24 2017 *) CROSSREFS Cf. A084712, A084713, A084714, A079706, A138066, A255707. Sequence in context: A187467 A081755 A237709 * A097859 A028326 A156046 Adjacent sequences:  A250197 A250198 A250199 * A250201 A250202 A250203 KEYWORD nonn AUTHOR Robert Price, Mar 02 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 21 06:14 EST 2021. Contains 340333 sequences. (Running on oeis4.)