A084924 - OEIS

A084924

Let t(x) be the highest power of 2 which divides x+1. Then a(1)=3; a(n) is the least prime p for which t(p) > t(a(n-1)).

3, 7, 31, 127, 1279, 3583, 5119, 6143, 8191, 81919, 131071, 524287, 14680063, 109051903, 654311423, 738197503, 2147483647, 21474836479, 51539607551, 824633720831, 13743895347199, 26388279066623, 246290604621823

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OFFSET

1,1

LINKS

M. F. Hasler, Table of n, a(n) for n = 1..100

EXAMPLE

a(5)=1279 because t(a(4))=7 and 1279 is the least prime with t(p)>7.

PROG

(PARI) a=vector(50); a[1]=3; for(i=2, length(a), j=k=2^(factor(a[i-1]+1, 2)[1, 2]+1); while(! isprime(j-1), j+=k); a[i]=j-1); a \\ M. F. Hasler, Mar 15 2007

CROSSREFS

Sequence in context: A354536 A138864 A105768 * A001348 A006515 A093535

Adjacent sequences: A084921 A084922 A084923 * A084925 A084926 A084927

KEYWORD

nonn

AUTHOR

Shane Findley, Jul 15 2003

EXTENSIONS

Edited by Don Reble, May 08 2004

More terms from M. F. Hasler, Mar 15 2007

STATUS

approved