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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}]]]]][[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: A189347 A248558 A372052 * 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 July 20 12:05 EDT 2024. Contains 374445 sequences. (Running on oeis4.)