A185910 Array: T(n,k) = n^2 + k - 1, by antidiagonals.
1, 2, 4, 3, 5, 9, 4, 6, 10, 16, 5, 7, 11, 17, 25, 6, 8, 12, 18, 26, 36, 7, 9, 13, 19, 27, 37, 49, 8, 10, 14, 20, 28, 38, 50, 64, 9, 11, 15, 21, 29, 39, 51, 65, 81, 10, 12, 16, 22, 30, 40, 52, 66, 82, 100, 11, 13, 17, 23, 31, 41, 53, 67, 83, 101, 121, 12, 14, 18, 24, 32, 42, 54, 68, 84, 102, 122, 144, 13, 15, 19, 25, 33, 43, 55, 69, 85, 103, 123, 145, 169, 14, 16, 20, 26, 34, 44, 56, 70, 86, 104, 124, 146, 170, 196
Offset: 1
Examples
Northwest corner: 1, 2, 3, 4, 5 4, 5, 6, 7, 8 9, 10, 11, 12, 13 16, 17, 18, 19, 20
Links
- G. C. Greubel, Table of n, a(n) for the first 50 antidiagonals, flattened
Programs
-
Mathematica
(* This program generates the array A185910, its accumulation array A185812, and its weight array A185911. *) f[n_,0]:=0;f[0,k_]:=0; f[n_,k_]:=n^2+k-1; TableForm[Table[f[n,k],{n,1,10},{k,1,15}]] (* A185910 *) 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}]; (* accumulation array of {f(n,k)} *) FullSimplify[s[n,k]] (* formula for A185812 *) TableForm[Table[s[n,k],{n,1,10},{k,1,15}]] Table[s[n-k+1,k],{n,14},{k,n,1,-1}]//Flatten w[m_,n_]:=f[m,n]+f[m-1,n-1]-f[m,n-1]-f[m-1,n]/;Or[m>0,n>0]; TableForm[Table[w[n,k],{n,1,10},{k,1,15}]] (* A185911 *) Table[w[n-k+1,k],{n,14},{k,n,1,-1}]//Flatten
Formula
T(n,k) = n^2 + k - 1, k >= 1, n >= 1.
Comments