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 | 0 |
| 2 | 2 |
| 3 | 10 |
| 4 | 46 |
| 5 | 192 |
| 6 | 780 |
| 7 | 3090 |
| 8 | 12136 |
| 9 | 47100 |
| 10 | 181820 |
| 11 | 697856 |
| 12 | 2667642 |
| 13 | 10157814 |
| 14 | 38563342 |
| 15 | 146002012 |
| 16 | 551483230 |
| 17 | 2078722874 |
| 18 | 7821121318 |
| 19 | 29378487188 |