A087930 Number of ways of arranging the numbers 1 ... 9n into a 9 X n array so there is exactly one local maximum.
256, 72545402880, 1811764909105311267840, 299167849199075018703047460201600
Offset: 1
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.