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 A120571 #15 Oct 21 2022 21:12:25
%S A120571 12,60,220,612,1404,2812,5100,8580,13612,20604,30012,42340,58140,
%T A120571 78012,102604,132612,168780,211900,262812,322404,391612,471420,562860,
%U A120571 667012,785004,918012,1067260,1234020,1419612,1625404,1852812,2103300,2378380
%N A120571 2n^4+6n^2+4 = 2(n^2+1)(n^2+2).
%C A120571 Largest perimeter of any triangle with integer sides a<=b<=c and inradius n. Triangle has sides (n^2+2,n^4+2n^2+1,n^4+3n^2+1).
%H A120571 David W. Wilson, <a href="/A120571/b120571.txt">Table of n, a(n) for n = 1..10000</a>
%H A120571 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5, -10, 10, -5, 1).
%F A120571 From _Chai Wah Wu_, Apr 15 2017: (Start)
%F A120571 a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n > 5.
%F A120571 G.f.: x*(-4*x^4 + 8*x^3 - 40*x^2 - 12)/(x - 1)^5. (End)
%t A120571 LinearRecurrence[{5,-10,10,-5,1},{12,60,220,612,1404},40] (* _Harvey P. Dale_, Dec 28 2018 *)
%o A120571 (PARI) a(n)=2*(n^2+1)*(n^2+2) \\ _Charles R Greathouse IV_, Oct 21 2022
%Y A120571 See A120062 for sequences related to integer-sided triangles with integer inradius n.
%K A120571 nonn,easy
%O A120571 1,1
%A A120571 _David W. Wilson_, Jun 17 2006