a(n) = Sum_{k=1..n+1} A027960(n+1, n+1+k).

Terms

a(0) =1a(1) =5a(2) =14a(3) =35a(4) =81a(5) =180a(6) =389a(7) =825a(8) =1726a(9) =3575a(10) =7349a(11) =15020a(12) =30561a(13) =61965a(14) =125294a(15) =252795a(16) =509161a(17) =1024100a(18) =2057549a(19) =4130225a(20) =8284926a(21) =16609455a(22) =33282989a(23) =66669660a(24) =133507081a(25) =267285605a(26) =535010414a(27) =1070731475a(28) =2142612801a(29) =4287086100