A339955 Numbers that are the sum of an odd square s and an even square t such that 0 < s < t.

5, 17, 25, 37, 45, 61, 65, 73, 89, 101, 109, 113, 125, 145, 149, 153, 169, 181, 193, 197, 205, 221, 225, 245, 257, 265, 277, 281, 305, 317, 325, 333, 337, 349, 365, 373, 377, 401, 405, 409, 425, 445, 449, 481, 485, 493, 509, 521, 533, 549, 565, 569, 577, 585, 601, 605, 613

Offset

1,1

Links

Table of n, a(n) for n=1..57.

Example

17 is in the sequence since 1^2 + 4^2 = 17, 1 is odd, 16 is even, and 0 < 1 < 16.

Mathematica

Table[If[Sum[Mod[i, 2] Mod[n - i + 1, 2] (Floor[Sqrt[i]] - Floor[Sqrt[i - 1]]) (Floor[Sqrt[n - i]] - Floor[Sqrt[n - i - 1]]), {i, Floor[n/2]}] > 0, n, {}], {n, 700}] // Flatten

Crossrefs

Cf. A000404, A010052, A057653, A097269.

Sequence in context: A343594 A063588 A307286 * A117635 A268526 A018447

Adjacent sequences: A339952 A339953 A339954 * A339956 A339957 A339958

Keyword

nonn

Author

Wesley Ivan Hurt, Dec 24 2020

Status

approved