Sum of n-th antidiagonal of array in A081998.

Terms

a(0) =1a(1) =5a(2) =16a(3) =50a(4) =118a(5) =248a(6) =434a(7) =713a(8) =1121a(9) =1624a(10) =2236a(11) =3158a(12) =4266a(13) =5486a(14) =6828a(15) =8344a(16) =10186a(17) =12006a(18) =14517a(19) =17225a(20) =20373a(21) =23907a(22) =27864a(23) =32150a(24) =37172a(25) =42199a(26) =47955a(27) =55292a(28) =62232a(29) =69367