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 A055745 #28 Apr 06 2024 09:03:11
%S A055745 1,2,6,10,22,30,42,58,70,78,102,130,190,210,330,462
%N A055745 Squarefree numbers not of form ab + bc + ca for 1 <= a <= b <= c (probably the list is complete).
%D A055745 Maohua Le, A note on positive integer solutions of the equation xy+yz+zx=n, Publ. Math. Debrecen 52 (1998) 159-165; Math. Rev. 98j:11016.
%H A055745 J. M. Borwein, <a href="https://carmamaths.org/resources/jon/OEIStalk.pdf">Adventures with the OEIS: Five sequences Tony may like</a>, Guttmann 70th [Birthday] Meeting, 2015, revised May 2016.
%H A055745 J. M. Borwein, <a href="/A060997/a060997.pdf">Adventures with the OEIS: Five sequences Tony may like</a>, Guttmann 70th [Birthday] Meeting, 2015, revised May 2016. [Cached copy, with permission]
%H A055745 J. Borwein and K.-K. S. Choi, <a href="https://projecteuclid.org/euclid.em/1046889597">On the representations of xy+yz+zx</a>, Experimental Mathematics, 9 (2000), 153-158.
%t A055745 solQ[n_, x_] := Reduce[1 <= y <= z && n == x*y + y*z + z*x, {y, z}, Integers] =!= False; solQ[n_] := Catch[xm = Ceiling[(n-1)/2]; For[x = 1, x <= xm, x++, Which[ solQ[n, x] === True, Throw[True], x == xm, Throw[False]]]] ; solQ[1] = False; Reap[ Do[ If[ SquareFreeQ[n], If[! solQ[n] , Print[n]; Sow[n]]], {n, 1, 500}]][[2, 1]] (* _Jean-François Alcover_, Jun 15 2012 *)
%Y A055745 Cf. A034168, A025052, A034169.
%K A055745 nonn,fini,nice
%O A055745 1,2
%A A055745 _N. J. A. Sloane_