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 | 2 |
| 2 | 4 |
| 3 | 13 |
| 4 | 50 |
| 5 | 248 |
| 6 | 1407 |
| 7 | 8600 |
| 8 | 55154 |
| 9 | 365292 |
| 10 | 2473956 |
| 11 | 17053468 |
| 12 | 119191992 |
| 13 | 842688120 |
| 14 | 6015275094 |
| 15 | 43292026736 |
| 16 | 313788095994 |
| 17 | 2288506113056 |
| 18 | 16781638172458 |
| 19 | 123656774440396 |
| 20 | 915123392599456 |