Fourth differences of Catalan numbers (A000108).

Terms

a(0) =3a(1) =9a(2) =30a(3) =102a(4) =352a(5) =1230a(6) =4344a(7) =15483a(8) =55626a(9) =201246a(10) =732564a(11) =2681223a(12) =9861342a(13) =36428320a(14) =135100620a(15) =502841295a(16) =1877678370a(17) =7032454470a(18) =26410804020a(19) =99437742720a(20) =375260126904