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 A087518 #5 Mar 31 2012 12:35:00 %S A087518 1,16,29568,35704394880,88366736882654697600 %N A087518 Number of arrangements of 1..n^2 in n X n array with exactly one local maximum. %C A087518 Neighbors of a cell are only considered in the X and Y directions. %C A087518 Number of ways to dig an n X n hole where each cell is at a different depth and water will collect in just one puddle. %C A087518 Computed using a C program, brute force enumeration except using a cache of old results to cut off the search tree. For many related problems however, R. H. Hardin has coded them in S/R (which is COSPAN's language). %e A087518 For n=2, 12 has only one local max., whereas 13 has two and is excluded. %e A087518 ........ 34 ................................ 42 %Y A087518 For the same problem with an n X 1 array see A000079. With no shape constraint, see A007846. Cf. A087519. Main diagonal of A087783. %K A087518 nonn,nice %O A087518 1,2 %A A087518 _R. H. Hardin_, Oct 23 2003