A047801 Number of different values of i^2+j^2+k^2+l^2 for i,j,k,l in [ 0,n ].
1, 5, 14, 29, 50, 74, 111, 149, 197, 247, 308, 370, 451, 526, 613, 706, 815, 914, 1037, 1146, 1284, 1416, 1565, 1698, 1876, 2030, 2209, 2380, 2578, 2757, 2972, 3168, 3401, 3612, 3850, 4071, 4339, 4575, 4843, 5089, 5388
Offset: 0
Links
- Robin Visser, Table of n, a(n) for n = 0..5000 (terms n = 0..100 from T. D. Noe).
Programs
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Mathematica
Table[ Length@Union@Flatten@Table[ i^2+j^2+k^2+l^2, {i, 0, n}, {j, i, n}, {k, j, n}, {l, k, n} ], {n, 0, 48} ]
Extensions
Definition corrected by Jonathan Vos Post, Nov 14 2007