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A321067 Considering Pythagorean triple (a,b,c) with a < b < c, least a such that there exists a primitive triple where c - b is the n-th term of A096033. 1

%I #19 Jan 03 2019 09:28:07

%S 3,8,20,33,48,65,88,119,140,204,207,252,297,336,396,429,540,555,616,

%T 696,731,832,893,1036,1113,1140,1248,1311,1428,1525,1692,1748,1809,

%U 1960,2059,2184,2325,2508,2576,2739,2832

%N Considering Pythagorean triple (a,b,c) with a < b < c, least a such that there exists a primitive triple where c - b is the n-th term of A096033.

%H Jean-François Alcover, <a href="/A321067/b321067.txt">Table of n, a(n) for n = 1..1000</a>

%e a(2) = 8 because in the primitive triple (8,15,17), c - b = A096033(2) = 2 and no smaller a yields a primitive triple where a < b < c and c - b = 2.

%t nmax = 100; kmax = 2;

%t A096033 = Union[2 Range[nmax]^2, (2 Range[0, Ceiling[nmax/Sqrt[2]]]+1)^2];

%t r[n_, k_] := Module[{a, b, c}, {a, b, c} /. {ToRules[Reduce[0 < a < b < c && c - b == A096033[[n]] && a^2 + b^2 == c^2, {a, b, c}, Integers] /. C[1] -> k]}];

%t a[n_] := a[n] = SelectFirst[Flatten[Table[r[n, k], {k, 1, kmax}], 1], GCD @@ # == 1 &] // First;

%t Table[Print[n, " ", a[n]]; a[n], {n, 1, 100}] (* _Jean-François Alcover_, Jan 01 2019 *)

%Y Cf. A096033, A094904.

%K nonn

%O 1,1

%A _Jeffrey Burch_, Oct 26 2018

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