id:A106821 - OEIS Search Results

Search: id:A106821

Displaying 1-1 of 1 results found.

page 1

Greatest k < n such that 2^n - 2^k -1 is prime or 0 if no such prime exists.

+0
1

0, 0, 2, 3, 3, 5, 0, 7, 7, 5, 3, 9, 11, 13, 0, 11, 11, 17, 11, 19, 17, 16, 0, 21, 13, 9, 0, 23, 17, 18, 0, 31, 23, 28, 31, 34, 0, 33, 0, 38, 31, 37, 0, 30, 43, 17, 31, 45, 41, 37, 7, 47, 41, 44, 0, 42, 55, 0, 27, 42, 43, 61, 0, 29 (list; graph; listen)

	OFFSET	`1,3`
	EXAMPLE	`2^3 - 2^2 -1 = 3 prime so a(3)=2` `2^4 - 2^3 -1 = 7 prime so a(4)=3` `2^5 - 2^3 -1 = 23 prime so a(5)=3` `2^6 - 2^5 -1 = 31 prime so a(6)=5`
	CROSSREFS	`Sequence in context: A128744 A118963 A127641 this_sequence A065863 A049272 A069461` `Adjacent sequences: A106818 A106819 A106820 this_sequence A106822 A106823 A106824`
	KEYWORD	`nonn`
	AUTHOR	`Pierre CAMI (pierrecami(AT)tele2.fr), May 18 2005`

page 1

Search completed in 0.002 seconds

Last modified November 27 22:38 EST 2009. Contains 167602 sequences.

AT&T Labs Research