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 A061042 #19 Oct 09 2023 11:21:19 %S A061042 1,400,144,784,64,1296,400,1936,18,2704,784,3600,256,4624,1296,5776, %T A061042 50,7056,1936,8464,576,10000,2704,11664,49,13456,3600,15376,1024, %U A061042 17424,4624,19600,81,21904,5776,24336,1600,26896,7056,29584 %N A061042 Denominator of 1/16 - 1/n^2. %H A061042 Reinhard Zumkeller, <a href="/A061042/b061042.txt">Table of n, a(n) for n = 4..10000</a> %H A061042 <a href="/index/Rec#order_72">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, -6, 0, 0, 0, 0, 0, 0, 0, 10, 0, 0, 0, 0, 0, 0, 0, -12, 0, 0, 0, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0, -10, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, -3, 0, 0, 0, 0, 0, 0, 0, 1). %F A061042 a(n) = 16*n^2 / gcd(16*n^2, n^2-16). - _Colin Barker_, Jan 13 2014 %t A061042 Denominator/@(1/16-1/Range[4,50]^2) (* _Harvey P. Dale_, May 14 2011 *) %o A061042 (Haskell) %o A061042 import Data.Ratio ((%), denominator) %o A061042 a061042 n = denominator (1%16 - 1%n^2) -- _Reinhard Zumkeller_, May 30 2012 %o A061042 (PARI) a(n)=denominator(1/16 - 1/n^2) \\ _Charles R Greathouse IV_, Feb 07 2017 %Y A061042 See A061041 for comments, references, links. %K A061042 nonn,frac,nice,easy %O A061042 4,2 %A A061042 _N. J. A. Sloane_, May 26 2001