Second differences of Catalan numbers A000108.

Terms

a(0) =1a(1) =2a(2) =6a(3) =19a(4) =62a(5) =207a(6) =704a(7) =2431a(8) =8502a(9) =30056a(10) =107236a(11) =385662a(12) =1396652a(13) =5088865a(14) =18642420a(15) =68624295a(16) =253706790a(17) =941630580a(18) =3507232740a(19) =13105289370a(20) =49114150020a(21) =184560753390a(22) =695267483664