A086719 Numbers n == 1, 2, 5 or 6 (mod 8) such that there is only one solution to i^2+j^2+k^2=n, i >= j >= k >= 0.

1, 2, 5, 6, 10, 13, 14, 21, 22, 30, 37, 42, 46, 58, 70, 78, 93, 133, 142, 190, 253

Offset

1,2

Links

Table of n, a(n) for n=1..21.

P. T. Bateman and E. Grosswald, Positive integers expressible as a sum of three squares in essentially only one way, J. Number Theory, 19 (1984), 301-308.

Mathematica

aQ[n_] := MemberQ[{1, 2, 5, 6}, Mod[n, 8]] && Length[Solve[i^2+j^2+k^2==n && k>=0 && j>=k && i>=j, {i, j, k}, Integers]]==1; Select[Range[260], aQ] (* Amiram Eldar, Dec 04 2018 *)

Crossrefs

Cf. A085616.

Sequence in context: A369166 A369211 A007674 * A115200 A075823 A368045

Adjacent sequences: A086716 A086717 A086718 * A086720 A086721 A086722

Keyword

nonn,fini,full

Author

N. J. A. Sloane, Jul 31 2003

Status

approved