|
| |
|
|
A078683
|
|
Least prime of the form n*2^m+1 for m>0, or 0 if there is no such prime.
|
|
2
|
|
|
|
3, 5, 7, 17, 11, 13, 29, 17, 19, 41, 23, 97, 53, 29, 31, 257, 137, 37, 1217, 41, 43, 89, 47, 97, 101, 53, 109, 113, 59, 61, 7937, 257, 67, 137, 71, 73, 149, 1217, 79, 641, 83, 337, 173, 89, 181, 11777
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
The next prime has 178 digits. See A078680 for the values of m.
|
|
|
LINKS
|
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
|
|
|
MATHEMATICA
|
Table[m=1; While[! PrimeQ[p = n*2^m + 1], m++]; p, {n, 50}]
|
|
|
PROG
|
(PARI) a(n)=if(n<0, 0, m=1; while(isprime(n*2^m+1)==0, m++); n*2^m+1)
|
|
|
CROSSREFS
|
Cf. A078680.
Sequence in context: A132445 A307437 A070846 * A099863 A112092 A031441
Adjacent sequences: A078680 A078681 A078682 * A078684 A078685 A078686
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Benoit Cloitre, Dec 17 2002
|
|
|
EXTENSIONS
|
Edited by T. D. Noe, Feb 25 2011
|
|
|
STATUS
|
approved
|
| |
|
|
