OFFSET
1,3
EXAMPLE
a(5) = 1 because C_4 (= 14) divides C_5 (= 42).
MAPLE
[seq(WCD(j), j=1..100)]; WCD := proc(n) local i; for i from n-1 by -1 to 0 do if(0 = (`mod`(Cat(n), Cat(i)))) then RETURN(n-i); fi; od; end; Cat := n -> (binomial(2*n, n)/(n+1));
MATHEMATICA
a[n_] := For[k = n - 1, True, k--, If[Divisible[CatalanNumber[n], CatalanNumber[k]], Return[n - k]]]; a[1] = 1; Array[a, 100] (* Jean-François Alcover, Mar 06 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 13 2001
STATUS
approved