OFFSET
1,1
COMMENTS
Primality up to Catalan(5885)-1 proved by PrimeForm.
The next term, if it exists, is > 60000. - Vaclav Kotesovec, Apr 26 2021
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
(PARI) is(n)=ispseudoprime(binomial(2*n, n)/(n+1)-1) \\ Charles R Greathouse IV, Jan 03 2014
(PFGW) ABC2 C(2*$a, $a)/($a+1)-1
a: from 5886 to 100000
Charles R Greathouse IV, Jan 03 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
David Broadhurst, Jan 10 2000
EXTENSIONS
a(34)-a(41) from Charles R Greathouse IV, Jan 03 2014
a(42) from Vaclav Kotesovec, Apr 20 2021
a(43)-a(46) from Vaclav Kotesovec, Apr 25 2021
STATUS
approved