A103963 Record values in A040081.

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

Offset: 1

Author

Lei Zhou, Feb 24 2005

Keywords

• nonn
• more

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.

Examples

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

Links

• Ray Ballinger and Wilfrid Keller, Riesel Problem

Crossrefs

Cf. A038699, A040081, A240113.

Programs

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}]]]

Extensions

Edited by T. D. Noe, Nov 15 2010