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 | 9 |
| 2 | 135 |
| 3 | 2460 |
| 4 | 49725 |
| 5 | 1072197 |
| 6 | 24163146 |
| 7 | 562311720 |
| 8 | 13409091540 |
| 9 | 325949656825 |
| 10 | 8046743477058 |
| 11 | 201198155083200 |
| 12 | 5084704634041305 |
| 13 | 129673310477725350 |
| 14 | 3332952595603387800 |
| 15 | 86250038091202771344 |
| 16 | 2245329811618166111985 |