A000451 Smallest number that is the sum of 3 squares in at least n ways.

0, 9, 41, 81, 146, 194, 306, 369, 425, 594, 689, 866, 1109, 1154, 1154, 1361, 1634, 1781, 1889, 2141, 2609, 2609, 3366, 3366, 3449, 3449, 3506, 4241, 4289, 4826, 5066, 5381, 5561, 5561, 6254, 7229, 7829, 8069, 8069, 8126, 8609, 8774, 8774

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Links

• T. D. Noe, Table of n, a(n) for n = 1..200
• Index entries for sequences related to sums of squares

Programs

Mathematica

nn = 100; lim = nn^2; t = Table[0, {lim}]; Do[k = x^2 + y^2 + z^2; If[0 < k <= lim, t[[k]]++], {x, 0, nn}, {y, x, nn}, {z, y, nn}]; u = Union[t]; c = Complement[Range[u[[-1]]], u]; If[c == {}, mx = u[[-1]], mx = c[[1]] - 1]; Join[{0}, Flatten[Table[Position[t, ?(# >= n &), 1, 1], {n, 2, mx}]]] (* _T. D. Noe, Jun 20 2012 *)