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A107290
Numbers (M_k+2)/3 where M_k is a Mersenne prime > 6.
0
3, 11, 43, 2731, 43691, 174763, 715827883, 768614336404564651, 206323339880896712483187371, 54086425609737787797192670096043, 56713727820156410577229101238628035243
OFFSET
3,1
COMMENTS
Many small values are prime; (M_89+2)/3 is the first composite.
CROSSREFS
Cf. A000668.
Sequence in context: A000979 A123628 A153476 * A302333 A377814 A345670
KEYWORD
nonn
AUTHOR
Yasutoshi Kohmoto, May 22 2005
EXTENSIONS
Edited by Don Reble, May 23 2005
STATUS
approved