Partial sums of A051878.

Terms

a(0) =1a(1) =14a(2) =77a(3) =280a(4) =798a(5) =1932a(6) =4158a(7) =8184a(8) =15015a(9) =26026a(10) =43043a(11) =68432a(12) =105196a(13) =157080a(14) =228684a(15) =325584a(16) =454461a(17) =623238a(18) =841225a(19) =1119272a(20) =1469930a(21) =1907620a(22) =2448810a(23) =3112200a(24) =3918915a(25) =4892706a(26) =6060159a(27) =7450912a(28) =9097880a(29) =11037488