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 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 21 |
| 7 | 52 |
| 8 | 135 |
| 9 | 368 |
| 10 | 1045 |
| 11 | 3068 |
| 12 | 9230 |
| 13 | 28245 |
| 14 | 87414 |
| 15 | 272544 |
| 16 | 854012 |
| 17 | 2685897 |
| 18 | 8473107 |
| 19 | 26805994 |
| 20 | 85045674 |
| 21 | 270599945 |
| 22 | 863529480 |
| 23 | 2763745020 |
| 24 | 8870777955 |
| 25 | 28550721966 |
| 26 | 92128996782 |
| 27 | 298004209496 |
| 28 | 966085311052 |