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 A289221 #9 Aug 13 2017 13:46:44 %S A289221 540,600,630,660,750,810,840,900,930,1050,1080,1320,1380,1500,1560, %T A289221 1590,1740,2040,2070,2280,2310,2520,2580,2970,3150,3240,3720,4020, %U A289221 4350,4530,4620,5460,6270,6300,7260,7560,7800,7980,11730,12210,14040,18870,22260,27030,27300,52530,103020 %N A289221 Areas of integer-sided triangles whose area equals 5 times their perimeter. %C A289221 There are no further terms. %e A289221 The areas 540,600,630,660,750, ... pertain respectively to triangles with sides (30,39,39), (30,40,50), (28,45,53), (26,51,55), (25,60,65)...., equal 5 times their perimeter 108,120,126,132,150,... %Y A289221 Cf. A098030, A289218, A289219, A289220. %Y A289221 A row of the triangle in A290451. %K A289221 fini,full,nonn %O A289221 1,1 %A A289221 _Zhining Yang_, Jun 28 2017