|
| |
|
|
A082387
|
|
Numbers n such that (5^n + 2^n)/7 is prime.
|
|
23
| |
|
|
3, 17, 19, 47, 101, 1709, 2539, 5591, 6037, 8011, 19373, 26489, 27427
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Next term > 35000. - Giovanni Resta (g.resta(AT)iit.cnr.it), Apr 06 2006
For (2^n + 5^n)/7 to be a prime n should be a prime too. - Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 06 2007
|
|
|
LINKS
| Primeform, User group for PFGW and PrimeForm programs
|
|
|
EXAMPLE
| a(1)=3 because (5^3+2^3)/7=(125+8)/7=19 is prime.
|
|
|
MATHEMATICA
| Do[f=(2^n+5^n)/7; If[PrimeQ[f], Print[{n, f}]], {n, 1, 35000}] - Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 06 2007
|
|
|
CROSSREFS
| Cf. A057469 = numbers n such that (2^n + 3^n)/5 is prime.
Sequence in context: A019342 A029473 A103088 * A032923 A018750 A177208
Adjacent sequences: A082384 A082385 A082386 * A082388 A082389 A082390
|
|
|
KEYWORD
| more,nonn
|
|
|
AUTHOR
| Hugo Pfoertner (hugo(AT)pfoertner.org), May 22 2003
|
|
|
EXTENSIONS
| More terms from Hugo Pfoertner (hugo(AT)pfoertner.org), Jun 23 2003
More terms from Giovanni Resta (g.resta(AT)iit.cnr.it), Apr 06 2006
|
| |
|
|
