cp's OEIS Frontend

A198436 Second term of a triple of squares in arithmetic progression, which is not a multiple of another triple in (A198384, A198385, A198386).

%I A198436 #40 Jan 31 2023 08:32:29
%S A198436 25,169,289,625,841,1369,1681,3721,2809,4225,4225,7225,5329,7225,7921,
%T A198436 10201,12769,9409,11881,15625,21025,21025,22201,18769,32761,24649,
%U A198436 29929,38809,34225,28561,48841,34225,37249,42025,52441,66049,70225,42025,48841,54289
%N A198436 Second term of a triple of squares in arithmetic progression, which is not a multiple of another triple in (A198384, A198385, A198386).
%H A198436 Ray Chandler, <a href="/A198436/b198436.txt">Table of n, a(n) for n = 1..10000</a>
%H A198436 Keith Conrad, <a href="http://www.math.uconn.edu/~kconrad/blurbs/ugradnumthy/3squarearithprog.pdf">Arithmetic progressions of three squares</a>
%H A198436 Reinhard Zumkeller, <a href="/A198435/a198435.txt">Table of initial values</a>
%F A198436 a(n) = A198440(n)^2 = A198385(A198409(n)).
%F A198436 a(n) - A198435(n) = A198437(n) - a(n) = A198438(n).
%t A198436 wmax = 1000;
%t A198436 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]];
%t A198436 tt = Flatten[DeleteCases[triples /@ Range[wmax], {}], 2];
%t A198436 DeleteCases[tt, t_List /; GCD @@ t>1 && MemberQ[tt, t/GCD @@ t]][[All, 2]] (* _Jean-François Alcover_, Oct 20 2021 *)
%o A198436 (Haskell)
%o A198436 a198436 n = a198436_list !! (n-1)
%o A198436 a198436_list = map a198385 a198409_list
%Y A198436 Cf. A198385, A198409, A198435, A198437, A198438, A198440.
%K A198436 nonn
%O A198436 1,1
%A A198436 _Reinhard Zumkeller_, Oct 25 2011