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 A147560 #29 May 01 2023 15:01:43
%S A147560 0,4,16,12,64,100,48,196,256,108,400,484,192,676,784,300,1024,1156,
%T A147560 432,1444,1600,588,1936,2116,768,2500,2704,972,3136,3364,1200,3844,
%U A147560 4096,1452,4624,4900,1728,5476,5776,2028,6400,6724,2352,7396,7744,2700,8464
%N A147560 a(n) = 4*A046162(n+1).
%H A147560 G. C. Greubel, <a href="/A147560/b147560.txt">Table of n, a(n) for n = 0..5000</a>
%F A147560 a(n) = 4*numerator(n^2/(n^2 + 3*n + 3)).
%F A147560 Sum_{n>=1} 1/a(n) = 11*Pi^2/216. - _Amiram Eldar_, Aug 14 2022
%F A147560 G.f.: 4*x*(1 + 4*x + 3*x^2 + 13*x^3 + 13*x^4 + 3*x^5 + 4*x^6 + x^7)/(1-x^3)^3. - _G. C. Greubel_, Oct 27 2022
%p A147560 A046162 := proc(n) (n-1)^2/(n^2+n+1) ; numer(%) ; end proc: A147560 := proc(n) 4*A046162(n+1) ; end proc: seq(A147560(n),n=0..70) ; # _R. J. Mathar_, Dec 15 2009
%t A147560 a[n_] := 4 * Numerator[n^2/(n^2 + 3*n + 3)]; Array[a, 50, 0] (* _Amiram Eldar_, Aug 14 2022 *)
%o A147560 (Magma) [4*Numerator(n^2/(n^2+3*n+3)): n in [0..70]]; // _G. C. Greubel_, Oct 27 2022
%o A147560 (SageMath) [4*numerator(n^2/(n^2 +3*n +3)) for n in range(71)] # _G. C. Greubel_, Oct 27 2022
%Y A147560 Companion to A144437.
%Y A147560 Cf. A046162.
%Y A147560 Cf. A171522. [_R. J. Mathar_, Dec 15 2009]
%K A147560 nonn,easy,less
%O A147560 0,2
%A A147560 _Paul Curtz_, Nov 07 2008
%E A147560 More terms from _R. J. Mathar_, Dec 15 2009