OFFSET
1,1
COMMENTS
Equivalently, numbers n such that the n-th central binomial coefficient C(2n,n) is divisible by 3n(n+1). - Joel B. Lewis, Jan 07 2008
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
MATHEMATICA
fQ[n_] := fQ[n_] := IntegerQ[ Binomial[2n, n]/(3n(n + 1))]; Select[ Range@681, fQ@# &]
With[{nn=700}, Transpose[Select[Thread[{CatalanNumber[Range[nn]], Range[ nn]}], Divisible[#[[1]], 3#[[2]]]&]][[2]]] (* Harvey P. Dale, Apr 30 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jun 19 2006
EXTENSIONS
Definition corrected by Joel B. Lewis, Apr 30 2009
STATUS
approved