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 | 12 |
| 3 | 74 |
| 4 | 466 |
| 5 | 2982 |
| 6 | 19320 |
| 7 | 126390 |
| 8 | 833220 |
| 9 | 5527190 |
| 10 | 36852052 |
| 11 | 246751854 |
| 12 | 1658106394 |
| 13 | 11176100138 |
| 14 | 75528743352 |
| 15 | 511600414554 |
| 16 | 3472363279170 |
| 17 | 23609924743590 |
| 18 | 160788499672020 |
| 19 | 1096566516149790 |
| 20 | 7488135911236806 |
| 21 | 51193972101241362 |
| 22 | 350368409215623192 |