This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A196119 #8 Mar 30 2012 18:57:49 %S A196119 3,4,5,6,7,7,8,8,9,9,10,11,11,12,12,12,13,13,14,14,15,15,15,16,16,16, %T A196119 16,17,17,18,18,19,19,20,20,20,20,20,21,21,21,21,22,22,23,23,24,24,24, %U A196119 24,24,25,25,25,26,26,27,27,28,28,28,28,28,28,29,30,30,30,31,32 %N A196119 Positive integers a for which there is a 4-Pythagorean triple (a,b,c) satisfying a<=b. %C A196119 See A195770 for definitions of k-Pythagorean triple, primitive k-Pythagorean triple, and lists of related sequences. %t A196119 z8 = 900; z9 = 250; z7 = 200; %t A196119 k = 4; c[a_, b_] := Sqrt[a^2 + b^2 + k*a*b]; %t A196119 d[a_, b_] := If[IntegerQ[c[a, b]], {a, b, c[a, b]}, 0] %t A196119 t[a_] := Table[d[a, b], {b, a, z8}] %t A196119 u[n_] := Delete[t[n], Position[t[n], 0]] %t A196119 Table[u[n], {n, 1, 15}] %t A196119 t = Table[u[n], {n, 1, z8}]; %t A196119 Flatten[Position[t, {}]] %t A196119 u = Flatten[Delete[t, Position[t, {}]]]; %t A196119 x[n_] := u[[3 n - 2]]; %t A196119 Table[x[n], {n, 1, z7}] (* A196119 *) %t A196119 y[n_] := u[[3 n - 1]]; %t A196119 Table[y[n], {n, 1, z7}] (* A196120 *) %t A196119 z[n_] := u[[3 n]]; %t A196119 Table[z[n], {n, 1, z7}] (* A196121 *) %t A196119 x1[n_] := If[GCD[x[n], y[n], z[n]] == 1, x[n], 0] %t A196119 y1[n_] := If[GCD[x[n], y[n], z[n]] == 1, y[n], 0] %t A196119 z1[n_] := If[GCD[x[n], y[n], z[n]] == 1, z[n], 0] %t A196119 f = Table[x1[n], {n, 1, z9}]; %t A196119 x2 = Delete[f, Position[f, 0]] (* A196122 *) %t A196119 g = Table[y1[n], {n, 1, z9}]; %t A196119 y2 = Delete[g, Position[g, 0]] (* A196123 *) %t A196119 h = Table[z1[n], {n, 1, z9}]; %t A196119 z2 = Delete[h, Position[h, 0]] (* A196124 *) %Y A196119 Cf. A195770, A196120, A196121, A196122. %K A196119 nonn %O A196119 1,1 %A A196119 _Clark Kimberling_, Sep 28 2011