|
|
A030239
|
|
a(n) is the smallest number k such that k*2^(2^n) + 1 is prime.
|
|
2
|
|
|
1, 1, 1, 1, 1, 18, 12, 21, 102, 202, 826, 708, 502, 1522, 6223, 3493, 1063, 50655, 10051, 328426
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,6
|
|
COMMENTS
|
The primality test for Proth numbers can be used. - Thomas Ordowski, Apr 13 2019
|
|
LINKS
|
|
|
FORMULA
|
a(n) = min{a : a > 0 and (a*2^2^n)! == -1 (mod a*2^2^n+1)}.
|
|
PROG
|
(PARI) isok(k, n) = isprime(k*2^(2^n) + 1);
a(n) = my(k=1); while (!isok(k, n), k++); k; \\ Michel Marcus, Apr 15 2019
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
Alar Leibak (aleibak(AT)cyber.ee)
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|