A135053 Greatest integer M(i)=n such that A085427(n)=A085427(n-1)/2 and k(i+1)>k(i) with A085427(n)=least k such that k*2^n-1 is prime ( Mersenne prime when k=1).

2, 21, 23, 80, 96, 111, 168, 230, 281, 347, 558, 704

Offset: 1

Author

Pierre CAMI, Nov 15 2007

Keywords

• nonn
• uned

Examples

			A085427 =3,2,1,1,2,1,2,1,5,7,5,3,2,1,5,4,2,1,2,1,14,7,26,13,39,22
A(2)=1,A(1)=2 so A(2)=A(1)/2 so M(1)=1
A(5)=1,A(4)=2 but A(5)=A(2) ..........
A(21)=7,A(20)=14 A(21)=A(20)/2 and A(21)>A(2) so M(2)=21
		

Crossrefs

Cf. A087425, A135054.