|
| |
|
|
A109835
|
|
Primes connected to two primes by the (p+1)/2 and 2p-1 operators.
|
|
3
| |
|
|
3, 37, 157, 661, 877, 997, 1237, 1657, 2137, 2557, 3061, 4177, 4261, 4357, 4621, 5581, 6037, 6121, 6217, 6361, 7537, 8317, 8461, 8521, 9241, 9277, 9721, 9901, 10837, 11497, 12241, 12421, 13417, 13681, 14737, 14821, 15121, 15277, 16417, 17257
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Primes involved in Cunningham chains of the second kind (2p-1) and not starting or ending them. A059455 is produced by the same rule, but "of the first kind (2p+1)"
|
|
|
LINKS
| Chris Caldwell's Prime Glossary, Cunningham chains.
|
|
|
EXAMPLE
| a(2)=37 is here because (37+1)/2=19 and (2*37)-1=73 are both primes;
a(11)=3061 because 1531->3061->6121 through <2p-1> and all primes;
a(11)=3061, a(18)=6121 and a(31)=12241 are here because they are "in" the complete Cunningham chain of the second kind 1531->3061->6121->12241->24481
|
|
|
MATHEMATICA
| Select[Prime[Range[5000]], PrimeQ[(#+1)/2]&&PrimeQ[2#-1]&] (* From Vladimir Joseph Stephan Orlovsky (4vladimir(AT)gmail.com), Nov 19 2010 *)
|
|
|
CROSSREFS
| Cf. A059455, A005385.
Sequence in context: A041067 A046867 A154823 * A066364 A106995 A120076
Adjacent sequences: A109832 A109833 A109834 * A109836 A109837 A109838
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), Aug 31 2005
|
| |
|
|
