OFFSET
1,1
COMMENTS
The 22nd term a(22) in the sequence has 862 digits.
a(23) has 1134 digits; a(25) has 1413 digits; a(30) has 2046 digits; a(31) has 2348 digits (these are not included in b-file).
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..22
EXAMPLE
a(2)= 41: n= 5: (2*n)!/(n!*(n + 1)!)-1= 41 which is prime.
a(4)= 1429: n= 8: (2*n)!/(n!*(n + 1)!)-1= 1429 which is prime.
MAPLE
KD:= proc() local a; a:= (2*n)!/(n!*(n + 1)!)-1; if isprime(a) then return(a): fi; end: seq(KD(), n=1..150);
MATHEMATICA
Select[CatalanNumber[Range[200]]-1, PrimeQ] (* Harvey P. Dale, Dec 21 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Nov 21 2013
STATUS
approved