A103963 Record values in A040081.

2, 3, 4, 7, 12, 23, 25, 2551, 800516

Offset

1,1

Comments

A040081(659) not yet found. The index sequence of this one is 1, 13, 23, 43, 59, 88, 127, 148, 659.

800516 was found by Dave Linton in 2004.

Links

Table of n, a(n) for n=1..9.

Ray Ballinger and Wilfrid Keller, Riesel Problem

Example

A040081(1)=2; A040081(13)=3; A040081(659)>8192

Mathematica

kmax=8192; k = 0; n = 0; km = k; While[k < kmax, n++; k = 0; cp = n*(2^k) - 1; While[(!PrimeQ[cp]) && (k < kmax), k++; cp = n*(2^k) - 1]; If[k > km, km = k; Print[{n, km}]]]

Crossrefs

Cf. A038699, A040081, A240113.

Sequence in context: A307673 A141002 A006537 * A006706 A194079 A124390

Adjacent sequences: A103960 A103961 A103962 * A103964 A103965 A103966

Keyword

nonn,more

Author

Lei Zhou, Feb 24 2005

Extensions

Edited by T. D. Noe, Nov 15 2010

Status

approved