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 A198384 First of a triple of squares in arithmetic progression. 15
 1, 4, 49, 9, 49, 16, 289, 196, 25, 1, 36, 196, 529, 49, 961, 441, 64, 1156, 81, 784, 441, 100, 2401, 289, 121, 2209, 4, 144, 1225, 529, 169, 784, 2601, 2116, 5041, 196, 3844, 1764, 49, 225, 256, 1681, 1225, 289, 1681, 2401, 6241, 9, 4624, 324, 9409, 361 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Ray Chandler, Table of n, a(n) for n = 1..10000 Keith Conrad, Arithmetic progressions of three squares Reinhard Zumkeller, Table of initial values FORMULA a(n) = A198388(n)^2. A198385(n) - a(n) = A198386(n) - A198385(n) = A198387(n). A198435(n) = a(A198409(n)). MATHEMATICA wmax = 1000; triples[w_] := Reap[Module[{u, v}, For[u = 1, u < w, u++, If[IntegerQ[v = Sqrt[(u^2 + w^2)/2]], Sow[{u^2, v^2, w^2}]]]]][]; Flatten[DeleteCases[triples /@ Range[wmax], {}], 2][[All, 1]] (* Jean-François Alcover, Oct 19 2021 *) PROG (Haskell) a198384 n = a198384_list !! (n-1) a198384_list = map (^ 2) a198388_list CROSSREFS Sequence in context: A058311 A189347 A248558 * A136196 A222960 A061100 Adjacent sequences:  A198381 A198382 A198383 * A198385 A198386 A198387 KEYWORD nonn AUTHOR Reinhard Zumkeller, Oct 24 2011 EXTENSIONS Thanks to Benoit Jubin, who had the idea for sequences A198384 .. A198390 and A198435 .. A198441. STATUS approved

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Last modified September 27 13:46 EDT 2022. Contains 357062 sequences. (Running on oeis4.)