|
|
A112863
|
|
Numbers k such that (2*k)!/(2*(k!)^2)+1 is prime.
|
|
5
|
|
|
1, 3, 5, 6, 14, 19, 24, 45, 49, 62, 72, 122, 149, 197, 209, 222, 349, 409, 491, 527, 601, 675, 728, 769, 795, 853, 1039, 1318, 1599, 2069, 2279, 2567, 2634, 3286, 3482, 6880, 6919, 9117, 9276, 9564, 10898, 13061, 14570, 16493, 17366, 18773, 19901, 25569, 26611, 28322
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
MATHEMATICA
|
Select[Range[3000], PrimeQ[(2#)!/(2(#!)^2)+1]&] (* James C. McMahon, Jun 13 2024 *)
|
|
PROG
|
(PARI) isok(k) = ispseudoprime(1+binomial(2*k-1, k-1)); \\ Michel Marcus, Jun 14 2024
|
|
CROSSREFS
|
|
|
KEYWORD
|
hard,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|