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 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 12 |
| 5 | 33 |
| 6 | 91 |
| 7 | 264 |
| 8 | 780 |
| 9 | 2365 |
| 10 | 7274 |
| 11 | 22727 |
| 12 | 71784 |
| 13 | 229094 |
| 14 | 737215 |
| 15 | 2390072 |
| 16 | 7798020 |
| 17 | 25587218 |
| 18 | 84377881 |
| 19 | 279499063 |
| 20 | 929556155 |
| 21 | 3102767833 |
| 22 | 10390936382 |
| 23 | 34903331506 |
| 24 | 117564309276 |
| 25 | 396994228503 |
| 26 | 1343716120550 |
| 27 | 4557952756658 |
| 28 | 15491856887741 |