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 A087924 #4 Mar 31 2012 12:35:01 %S A087924 4,208,29568,7452704,2941306368,1683453629440,1323082429842432, %T A087924 1370418864769445888,1811764909105311267840,2980039854936078219167744, %U A087924 5972307516078119199647692800 %N A087924 Number of ways of arranging the numbers 1 ... 3n into a 3 X n array so there is exactly one local maximum. %Y A087924 A row of the array in A087783. Cf. A007846. %K A087924 nonn %O A087924 1,1 %A A087924 _R. H. Hardin_, Oct 27 2003