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 | 3 |
| 4 | 9 |
| 5 | 31 |
| 6 | 113 |
| 7 | 431 |
| 8 | 1697 |
| 9 | 6847 |
| 10 | 28161 |
| 11 | 117631 |
| 12 | 497665 |
| 13 | 2128127 |
| 14 | 9183489 |
| 15 | 39940863 |
| 16 | 174897665 |
| 17 | 770452479 |
| 18 | 3411959809 |
| 19 | 15181264895 |
| 20 | 67833868289 |
| 21 | 304256253951 |
| 22 | 1369404661761 |
| 23 | 6182858317823 |
| 24 | 27995941060609 |
| 25 | 127100310290431 |
| 26 | 578433619525633 |
| 27 | 2638370120138751 |