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 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 13 |
| 6 | 42 |
| 7 | 146 |
| 8 | 476 |
| 9 | 1574 |
| 10 | 5122 |
| 11 | 16706 |
| 12 | 54256 |
| 13 | 176254 |
| 14 | 571954 |
| 15 | 1856245 |
| 16 | 6023681 |
| 17 | 19551939 |
| 18 | 63476314 |
| 19 | 206145075 |
| 20 | 669695819 |
| 21 | 2176401235 |
| 22 | 7075521724 |
| 23 | 23011145314 |
| 24 | 74864599954 |
| 25 | 243652588070 |
| 26 | 793264765396 |
| 27 | 2583532274289 |
| 28 | 8416929889967 |
| 29 | 27430452311513 |