|
|
A053427
|
|
Numbers n such that Catalan(n)-1 is prime.
|
|
3
|
|
|
4, 5, 6, 8, 9, 18, 25, 66, 87, 134, 145, 200, 384, 443, 502, 589, 625, 638, 1082, 1235, 1236, 1439, 1892, 2014, 2355, 2380, 2592, 2676, 2981, 3406, 3908, 4775, 5885, 10617, 16108, 17035, 18164, 18307, 20565, 24542, 26388, 32786, 47379, 49711, 50103, 55067
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
Primality up to Catalan(5885)-1 proved by PrimeForm.
|
|
LINKS
|
|
|
EXAMPLE
|
Catalan(25)-1 = 50!/25!/26!-1 = 4861946401451 is prime.
|
|
MATHEMATICA
|
Reap[ Do[ If[ PrimeQ[ CatalanNumber[n] - 1], Print[n]; Sow[n]], {n, 0, 10^4}]][[2, 1]] (* Jean-François Alcover, Feb 02 2015 *)
|
|
PROG
|
(PFGW) ABC2 C(2*$a, $a)/($a+1)-1
a: from 5886 to 100000
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|