OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
filter:= proc(n) local L1, L2, L3;
L1:= convert(2*n, base, 3);
L2:= convert(n, base, 3);
L3:= convert(n-1, base, 3);
mul(binomial(L1[i], L2[i]), i=1..nops(L2)) - mul(binomial(L1[i], L3[i]), i=1..nops(L3)) mod 3 = 2
end proc:
select(filter, [$1..1000]); # Robert Israel, Jun 30 2020
MATHEMATICA
Flatten[Position[CatalanNumber[Range[750]], _?(Mod[#, 3]==2&)]] (* Harvey P. Dale, Sep 21 2012 *)
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Robert G. Wilson v, Sep 09 2005
STATUS
approved