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 A335640 Numbers k of the form r^2 - t*r*s + s^2, where r, s and t are positive integers, r + s = k and t < r <= s. 0
 4, 9, 16, 25, 36, 45, 49, 64, 81, 96, 100, 121, 144, 169, 175, 196, 225, 256, 288, 289, 320, 324, 361, 400, 441, 484, 529, 576, 625, 640, 676, 729, 784, 841, 891, 900, 961, 1024, 1089, 1156, 1200, 1225, 1296, 1350, 1369, 1444, 1521, 1573, 1600, 1681, 1764, 1849, 1936, 2016 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE 9 is in the sequence since 9 = 3^2 - 2*3*6 + 6^2. MATHEMATICA Table[If[Sum[Sum[KroneckerDelta[i^2 - k*i (n - i) + (n - i)^2, n], {k, i - 1}], {i, Floor[n/2]}] > 0, n, {}], {n, 200}] // Flatten CROSSREFS Sequence in context: A070459 A292676 A241971 * A302053 A162496 A159852 Adjacent sequences: A335637 A335638 A335639 * A335641 A335642 A335643 KEYWORD nonn AUTHOR Wesley Ivan Hurt, Oct 04 2020 STATUS approved

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Last modified December 4 21:40 EST 2022. Contains 358570 sequences. (Running on oeis4.)