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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 26 |
| 4 | 240 |
| 5 | 2876 |
| 6 | 42372 |
| 7 | 740536 |
| 8 | 14970816 |
| 9 | 343603216 |
| 10 | 8825080100 |
| 11 | 250756091552 |
| 12 | 7809130867824 |
| 13 | 264489160965056 |
| 14 | 9678967816041188 |
| 15 | 380574552503498624 |
| 16 | 16000787866533953280 |
| 17 | 716309568462681538816 |