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 A165727 #13 Mar 30 2012 18:52:03 %S A165727 0,0,0,0,1,0,0,4,4,0,0,9,1,9,0,0,16,36,36,16,0,0,25,16,1,16,25,0,0,36, %T A165727 100,144,144,100,36,0,0,49,9,225,1,225,9,49,0,0,64,196,12,400,400,12, %U A165727 196,64,0,0,81,64,441,144,1,144,441,64,81,0,0,100,324,576,784,900,900,784,576,324,100,0 %N A165727 Table T(k,n) read by antidiagonals: denominator of 1/min(n,k)^2 -1/max(n,k)^2 with T(0,n) = T(k,0) = 0. %C A165727 A synopsis of the denominators of the transitions in the Rydberg-Ritz spectrum of hydrogenic atoms. %H A165727 Alois P. Heinz, <a href="/A165727/b165727.txt">Table of n, a(n) for n = 0..1034</a> %e A165727 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ... A000004 %e A165727 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, ... A000290 %e A165727 0, 4, 1, 36, 16, 100, 9, 196, 64, 324, ... A061038 %e A165727 0, 9, 36, 1, 144, 225, 12, 441, 576, 81, ... A061040 %e A165727 0, 16, 16, 144, 1, 400, 144, 784, 64, 1296, ... A061042 %e A165727 0, 25, 100, 225, 400, 1, 900, 1225, 1600, 2025, ... A061044 %e A165727 0, 36, 9, 12, 144, 900, 1, 1764, 576, 324, ... A061046 %e A165727 0, 49, 196, 441, 784, 1225, 1764, 1, 3136, 3969, ... A061048 %e A165727 0, 64, 64, 576, 64, 1600, 576, 3136, 1, 5184, ... A061050 %e A165727 0, 81, 324, 81, 1296, 2025, 324, 3969, 5184, 1, ... %p A165727 T:= (k,n)-> `if` (n=0 or k=0, 0, denom (1/min (n,k)^2 -1/max (n, k)^2)): %p A165727 seq (seq (T (k, d-k), k=0..d), d=0..11); %Y A165727 Cf. A165441 (top row and left column removed) %K A165727 nonn,tabl,frac,easy %O A165727 0,8 %A A165727 _Paul Curtz_, Sep 25 2009 %E A165727 Edited by _R. J. Mathar_, Feb 27 2010, Mar 03 2010