A098471 Least k such that Mersenne-prime(n)*2^k+1 is prime (A000668(n)*2^k+1).

1, 2, 8, 2, 12, 864, 4, 10, 8, 72, 18, 38, 2144, 178, 472, 974, 2200, 8128, 4580, 822, 3600, 4100

Offset

1,2

Links

Table of n, a(n) for n=1..22.

Mathematica

mexp = {the list in A000043}; f[n_] := Block[{k = 1, mp = 2^mexp[[n]] - 1}, While[ !PrimeQ[mp*2^k + 1] && k < 10000, k++ ]; If[k == 10000, 0, k]]; Do[ Print[ f[n]], {n, 22}] (* Robert G. Wilson v, Sep 13 2004 *)

Crossrefs

Cf. A098472.

Sequence in context: A195844 A222828 A222842 * A341533 A341741 A074723

Adjacent sequences: A098468 A098469 A098470 * A098472 A098473 A098474

Keyword

nonn

Author

Pierre CAMI, Sep 09 2004

Extensions

a(18)-a(22) from Robert G. Wilson v, Sep 13 2004

Status

approved