|
|
A261578
|
|
Numbers m such that (4^m + 17) / 3 is prime.
|
|
1
|
|
|
1, 2, 5, 8, 11, 23, 26, 59, 83, 89, 116, 1103, 1568, 5768, 13376, 17810, 18614, 66209, 167933, 188318
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
After 1, m is of the form 3*k+2. In fact, for m = 3*k or 3*k+1, 4^n+17 is divisible by 9 and 7, respectively. [Bruno Berselli, Aug 26 2015]
|
|
LINKS
|
|
|
EXAMPLE
|
2 is in the sequence because (4^2+17)/3 = 11 is prime.
5 is in the sequence because (4^5+17)/3 = 347 is prime.
|
|
MATHEMATICA
|
Select[Range[0, 5000], PrimeQ[(4^# + 17)/3] &]
|
|
PROG
|
(Magma) [n: n in [0..1000] | IsPrime((4^n+17) div 3)];
(PARI) for(n=1, 1e3, if(isprime((4^n+17)/3), print1(n", "))) \\ Altug Alkan, Sep 14 2015
|
|
CROSSREFS
|
Cf. similar sequences listed in A261539.
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|