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 A165919 #6 May 01 2013 21:13:44 %S A165919 4,4,4,4,4,4,9,4,9,4,9,4,9,12,4,8,9,4,9,4,9,4,8,9,16,4,9,16,4,9,16,4, %T A165919 9,16,4,9,16,18,4,9,12,16,20,4,8,9,12,16,18,4,9,12,16,4,9,16,24,4,9, %U A165919 12,16,25,4,9,16,25,4,8,9,16,25,4,9,16,20,24,25,28,4,9,16,24,25 %N A165919 Irregular triangle read by rows: square-full nonzero quadratic residues mod n. %C A165919 The irregular triangle of numbers is: %C A165919 ..n....Square-full nonzero quadratic residues %C A165919 ..1.... %C A165919 ..2.... %C A165919 ..3.... %C A165919 ..4.... %C A165919 ..5.....4 %C A165919 ..6.....4 %C A165919 ..7.....4 %C A165919 ..8.....4 %C A165919 ..9.....4 %C A165919 .10.....4..9 %C A165919 .11.....4..9 %C A165919 .12.....4..9 %C A165919 .13.....4..9.12 %C A165919 .14.....4..8..9 %C A165919 .15.....4..9 %C A165919 .16.....4..9 %C A165919 .17.....4..8..9.16 %C A165919 .18.....4..9.16 %C A165919 .19.....4..9.16 %C A165919 .20.....4..9.16 %C A165919 .21.....4..9.16.18 %C A165919 .22.....4..9.12.16.20 %C A165919 .23.....4..8..9.12.16.18 %C A165919 .24.....4..9.12.16 %C A165919 .25.....4..9.16.24 %C A165919 .26.....4..9.12.16.25 %C A165919 .27.....4..9.16.25 %C A165919 .28.....4..8..9.16.25 %C A165919 .29.....4..9.16.20.24.25 %C A165919 .30.....4..9.16.24.25 %H A165919 C. H. Gribble, <a href="/A165919/b165919.txt">Flattened irregular triangle read by rows as table of j, a(j) for j = 5..69744 (rows 5:1000)</a>. [Entries in b-file edited by _N. J. A. Sloane_, Oct 04 2010] %Y A165919 Cf. A046071. %K A165919 nonn,tabf %O A165919 5,1 %A A165919 _Christopher Hunt Gribble_, Sep 30 2009 %E A165919 Minor edit and cross-reference added by _Christopher Hunt Gribble_, Oct 05 2009 %E A165919 Offset set to 5, keyword:tabf added - _R. J. Mathar_, Oct 09 2009