|
|
A046865
|
|
Numbers k such that 4*5^k - 1 is prime.
|
|
16
|
|
|
0, 1, 3, 9, 13, 15, 25, 39, 69, 165, 171, 209, 339, 2033, 6583, 15393, 282989, 498483, 504221, 754611, 864751
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
COMMENTS
|
|
|
REFERENCES
|
R. K. Guy, Unsolved Problems in Number Theory, Section A3.
|
|
LINKS
|
|
|
MATHEMATICA
|
Print[0]; Do[ If[ PrimeQ[4*5^n - 1], Print[n]], {n, 1, 8100, 2}]
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,hard,nice,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
a(16) from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
|
|
STATUS
|
approved
|
|
|
|