A185913 Accumulation array of A185912, by antidiagonals.
1, 4, 6, 10, 21, 20, 20, 48, 66, 50, 35, 90, 144, 160, 105, 56, 150, 260, 340, 330, 196, 84, 231, 420, 600, 690, 609, 336, 120, 336, 630, 950, 1200, 1260, 1036, 540, 165, 468, 896, 1400, 1875, 2170, 2128, 1656, 825, 220, 630, 1224, 1960, 2730, 3360, 3640, 3384, 2520, 1210, 286, 825, 1620, 2640, 3780, 4851, 5600, 5760, 5130, 3685, 1716, 364, 1056, 2090, 3450, 5040, 6664, 8036, 8820, 8700, 7480, 5214, 2366, 455
Offset: 1
Examples
Northwest corner: 1.....4.....10.....20.....35 6.....21....48.....90.....150 20....66....144....260....420 50....160...340....600....950
Links
- G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
Programs
-
Mathematica
(* The program generates A185912 and its accumulation array A185913 *) f[n_,k_]:=(k*n/6)(-2+3k+3n+2n^2); TableForm[Table[f[n,k],{n,1,10},{k,1,15}]] (* array A185912 *) Table[f[n-k+1,k],{n,14},{k,n,1,-1}]//Flatten s[n_,k_]:=Sum[f[i,j],{i,1,n},{j,1,k}]; FullSimplify[s[n,k]] (* formula for A185913 *) TableForm[Table[s[n,k],{n,1,10},{k,1,15}]] (* array A185913 *) Table[s[n-k+1,k],{n,14},{k,n,1,-1}]//Flatten
Formula
T(n,k) = C(k+1,2)*C(n+1,2)*(n^2+3*n+2*k)/6, k>=1, n>=1.
Comments