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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). 1
2, 21, 23, 80, 96, 111, 168, 230, 281, 347, 558, 704 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..12.

EXAMPLE

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.

Sequence in context: A322925 A294116 A041513 * A042565 A079907 A075715

Adjacent sequences:  A135050 A135051 A135052 * A135054 A135055 A135056

KEYWORD

nonn,uned

AUTHOR

Pierre CAMI, Nov 15 2007

STATUS

approved

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Last modified June 20 05:01 EDT 2019. Contains 324229 sequences. (Running on oeis4.)