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

Offset: 1

Author

Shane Findley, Jul 15 2003

Keywords

• nonn

Examples

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

Links

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

Programs

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

Extensions

Edited by Don Reble, May 08 2004

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