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 A218487 #17 Apr 18 2021 14:40:01
%S A218487 720,5040,5760,10080,20160,22176,28800,56160,60480,100800,126720,
%T A218487 134640,151200,187200,248976,262080,282240,332640,428400,443520,
%U A218487 463680,665280,677376,734400,763776,887040,1108800,1149120,1190160,1235520,1497600,1685376,1718640
%N A218487 Positive numbers differing from next 3 greater squares by squares.
%C A218487 All terms are multiples of 144. - _Zak Seidov_, Nov 27 2013
%H A218487 Donovan Johnson, <a href="/A218487/b218487.txt">Table of n, a(n) for n = 1..1000</a>
%H A218487 E. J. Barbeau, <a href="http://dx.doi.org/10.4153/CMB-1985-040-9">Numbers differing from consecutive squares by squares</a>, Canad. Math. Bull. 28(1985), pp. 337-342.
%e A218487 720 = 27^2 - 3^2 = 28^2 - 8^2 = 29^2 - 11^2.
%t A218487 Select[Range[172*10^4],AllTrue[Sqrt[(Floor[Sqrt[#]]+{1,2,3})^2-#],IntegerQ]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 18 2021 *)
%o A218487 (PARI) sq3(n) = {for (i=1, n, a = sqrtint(i) + 1; if (issquare(a^2-i) && issquare((a+1)^2-i) && issquare((a+2)^2-i), print1(i, ", ")););}
%Y A218487 Cf. A218485, A218486, A218488.
%K A218487 nonn
%O A218487 1,1
%A A218487 _Michel Marcus_, Oct 30 2012