Apply partial sum operator twice to Catalan numbers.

Terms

a(0) =1a(1) =3a(2) =7a(3) =16a(4) =39a(5) =104a(6) =301a(7) =927a(8) =2983a(9) =9901a(10) =33615a(11) =116115a(12) =406627a(13) =1440039a(14) =5147891a(15) =18550588a(16) =67310955a(17) =245716112a(18) =901759969a(19) =3325067016a(20) =12312494483a(21) =45766188970a(22) =170702447097a(23) =638698318874