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 | 15 |
| 5 | 46 |
| 6 | 147 |
| 7 | 486 |
| 8 | 1646 |
| 9 | 5684 |
| 10 | 19940 |
| 11 | 70864 |
| 12 | 254592 |
| 13 | 923153 |
| 14 | 3374046 |
| 15 | 12417246 |
| 16 | 45975677 |
| 17 | 171141378 |
| 18 | 640105278 |
| 19 | 2404375805 |
| 20 | 9066188052 |
| 21 | 34305301482 |
| 22 | 130219435385 |
| 23 | 495735347502 |
| 24 | 1892254721982 |
| 25 | 7240580768021 |
| 26 | 27768359445128 |
| 27 | 106718055778871 |