|
| |
|
|
A164620
|
|
Primes p such that 1 +p*floor(p/2) is also prime.
|
|
3
| |
|
|
2, 5, 13, 17, 41, 61, 89, 97, 101, 113, 149, 173, 229, 241, 281, 317, 349, 353, 373, 397, 409, 421, 433, 461, 509, 521, 661, 673, 761, 853, 881, 937, 941, 1013, 1093, 1109, 1249, 1289, 1297, 1373, 1433, 1549, 1741, 1753, 1913, 2113, 2213, 2269, 2281, 2297
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
EXAMPLE
| p=2 qualifies since 2*1+1=3 is prime. p=5 qualifies since 5*2+1=11 is prime.
|
|
|
MATHEMATICA
| lst={}; Do[p=Prime[n]; If[PrimeQ[p*Floor[p/2]+1], AppendTo[lst, p]], {n, 3*6!}]; lst
|
|
|
CROSSREFS
| Cf. A008846, A020882, A158708
Sequence in context: A079936 A102854 A156009 * A156013 A112634 A045364
Adjacent sequences: A164617 A164618 A164619 * A164621 A164622 A164623
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 17 2009
|
|
|
EXTENSIONS
| Comments turned into examples by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 17 2009
|
| |
|
|
