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.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 52 |
| 3 | 880 |
| 4 | 17856 |
| 5 | 399296 |
| 6 | 9491008 |
| 7 | 235274240 |
| 8 | 6014201600 |
| 9 | 157387037696 |
| 10 | 4195621863424 |
| 11 | 113534211297280 |
| 12 | 3110485641494528 |
| 13 | 86107512380129280 |
| 14 | 2404899661362184192 |
| 15 | 67680890349732102144 |
| 16 | 1917436905101367443456 |
| 17 | 54640222663002565640192 |
| 18 | 1565130555077611323392000 |
| 19 | 45039415225401829826232320 |