Sums of antidiagonals of A099233.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =9a(5) =18a(6) =39a(7) =91a(8) =226a(9) =594a(10) =1643a(11) =4763a(12) =14419a(13) =45444a(14) =148714a(15) =504150a(16) =1766930a(17) =6390720a(18) =23815168a(19) =91306968a(20) =359694457a(21) =1454213026a(22) =6027213531a(23) =25583995337a(24) =111118605583a(25) =493407322280