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A135054
Greatest integer K(i)=A085427(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
1, 7, 13, 15, 17, 75, 102, 173, 181, 229, 513, 539
OFFSET
1,2
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 K(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 K(2)=7
CROSSREFS
Sequence in context: A328254 A347637 A191976 * A076701 A224773 A349749
KEYWORD
nonn,uned
AUTHOR
Pierre CAMI, Nov 15 2007
STATUS
approved