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 | 4 |
| 3 | 13 |
| 4 | 44 |
| 5 | 153 |
| 6 | 544 |
| 7 | 1965 |
| 8 | 7185 |
| 9 | 26536 |
| 10 | 98822 |
| 11 | 370593 |
| 12 | 1398029 |
| 13 | 5300984 |
| 14 | 20189792 |
| 15 | 77198271 |
| 16 | 296202907 |
| 17 | 1140024698 |
| 18 | 4399918134 |
| 19 | 17024040984 |
| 20 | 66018733123 |
| 21 | 256549059895 |
| 22 | 998839762846 |
| 23 | 3895616434744 |
| 24 | 15217813245743 |
| 25 | 59534874351097 |
| 26 | 233231355731136 |
| 27 | 914864639728729 |