id:A104280 - OEIS Search Results

Search: id:A104280

Displaying 1-1 of 1 results found.

page 1

Numbers n such that 2n+1 is not prime and 2n-1 is prime.

+0
2

4, 7, 10, 12, 16, 19, 22, 24, 27, 31, 34, 37, 40, 42, 45, 49, 52, 55, 57, 64, 66, 70, 76, 79, 82, 84, 87, 91, 97, 100, 106, 112, 115, 117, 121, 126, 129, 132, 136, 139, 142, 147, 154, 157, 159, 166, 169, 175, 177, 180, 184, 187, 190, 192, 195, 199, 201, 205, 211, 217 (list; graph; listen)

	OFFSET	`1,1`
	MATHEMATICA	`Select[ Range[219], !PrimeQ[2# + 1] && PrimeQ[2# - 1] &] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 18 2005)`
	CROSSREFS	`Cf. A040040 and others.` `Sequence in context: A078633 A103762 A080734 this_sequence A083032 A020965 A065713` `Adjacent sequences: A104277 A104278 A104279 this_sequence A104281 A104282 A104283`
	KEYWORD	`easy,nonn`
	AUTHOR	`Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), Apr 17 2005`
	EXTENSIONS	`More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 18 2005`

page 1

Search completed in 0.005 seconds

Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

AT&T Labs Research