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 | 4 |
| 2 | 140 |
| 3 | 7084 |
| 4 | 420732 |
| 5 | 27343888 |
| 6 | 1882933364 |
| 7 | 134993766600 |
| 8 | 9969937491420 |
| 9 | 753310723010608 |
| 10 | 57956002331347120 |
| 11 | 4524678117939182220 |
| 12 | 357557785658996609700 |
| 13 | 28545588568201512137904 |
| 14 | 2298872717007844035521848 |
| 15 | 186533392975795702301759056 |