Stepped path in P(k,n) array of k-th partial sums of squares (A000290).

Terms

a(0) =1a(1) =5a(2) =6a(3) =20a(4) =27a(5) =77a(6) =112a(7) =294a(8) =450a(9) =1122a(10) =1782a(11) =4290a(12) =7007a(13) =16445a(14) =27456a(15) =63206a(16) =107406a(17) =243542a(18) =419900a(19) =940576a(20) =1641486a(21) =3640210a(22) =6418656a(23) =14115100a(24) =25110020a(25) =54826020a(26) =98285670a(27) =213286590a(28) =384942375