A181692 The smallest positive m such that 2^m-2^n-1 is prime, or 0 if such an m does not exist.

2, 3, 3, 4, 6, 6, 8, 8, 14, 12, 14, 13, 20, 14, 18, 24, 22, 18, 20, 20, 38, 24, 42, 28, 32, 32, 50, 59, 34, 32, 44, 32, 38, 38, 36, 40, 48, 42, 40, 45, 48, 45, 56, 45, 54, 48, 76, 52, 68, 66, 100, 89, 80, 74, 80, 57, 66, 78, 98, 83, 162, 62, 166, 77, 66, 77, 72, 76, 74, 153, 80, 89, 86, 77, 94, 83, 78, 88, 110, 115, 84

Offset

0,1

Links

Amiram Eldar, Table of n, a(n) for n = 0..3000

Maple

A181692 := proc(n) for m from n to 100000 do if isprime(2^m-2^n-1) then return m; end if; end do: return 0 ; end proc:

Mathematica

m[n_]:=Module[{m=n+1}, While[!PrimeQ[2^m-2^n-1], m++]; m]
Table[m[i], {i, 90}] (* Harvey P. Dale, Dec. 18, 2010 *)

Prog

(PARI) for(n=0, 80, for(m=n+1, oo, k=2^m-2^n-1; if(isprime(k), print1(m, ", "); break))) \\ Hugo Pfoertner, Jan 12 2020

Crossrefs

Cf. A096502.

Sequence in context: A348540 A118096 A296440 * A145806 A100989 A188215

Adjacent sequences: A181689 A181690 A181691 * A181693 A181694 A181695

Keyword

nonn

Author

Vladimir Shevelev, Nov 05 2010

Extensions

a(12) corrected and sequence extended by R. J. Mathar, Nov 17 2010

Status

approved