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 A152020 #27 Sep 14 2022 02:04:27
%S A152020 1,1,9,2,25,9,49,8,81,25,121,18,169,49,225,32,289,81,361,50,441,121,
%T A152020 529,72,625,169,729,98,841,225,961,128,1089,289,1225,162,1369,361,
%U A152020 1521,200,1681,441,1849,242,2025,529,2209,288,2401,625
%N A152020 Denominator of 8/(9n^2) divided by 9.
%H A152020 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,3,0,0,0,-3,0,0,0,1).
%F A152020 a(n) = A152018(n)/9.
%F A152020 a(1)=1, a(2)=1, a(3)=9, a(4)=2, a(5)=25, a(6)=9, a(7)=49, a(8)=8, a(9)=81, a(10)=25, a(11)=121, a(12)=18, a(n)=3*a(n-4)-3*a(n-8)+a(n-12). - _Harvey P. Dale_, Aug 25 2013
%F A152020 Conjecture: a(n) = denominator((n-2)^3/n^2). - _Andres Cicuttin_, Sep 19 2017
%F A152020 a(n) = n^2/gcd(n^2, 8). - _Andrew Howroyd_, Jul 25 2018
%F A152020 Sum_{n>=1} 1/a(n) = Pi^2/3 (A195055). - _Amiram Eldar_, Sep 14 2022
%t A152020 Denominator[8/(9*Range[50]^2)]/9 (* or *) LinearRecurrence[{0, 0, 0, 3, 0, 0, 0, -3, 0, 0, 0, 1}, {1, 1, 9, 2, 25, 9, 49, 8, 81, 25, 121, 18}, 50] (* _Harvey P. Dale_, Aug 25 2013 *)
%o A152020 (PARI) a(n) = denominator(8/(9*n^2))/9 \\ _Michel Marcus_, Jun 01 2013
%Y A152020 Cf. A152018, A195055.
%K A152020 nonn,mult
%O A152020 1,3
%A A152020 _Paul Curtz_, Nov 20 2008
%E A152020 More terms from _Michel Marcus_, Jun 01 2013
%E A152020 Keyword:mult added by _Andrew Howroyd_, Jul 25 2018