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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 16 |
| 5 | 54 |
| 6 | 178 |
| 7 | 565 |
| 8 | 1770 |
| 9 | 5493 |
| 10 | 16927 |
| 11 | 51901 |
| 12 | 158533 |
| 13 | 482802 |
| 14 | 1466859 |
| 15 | 4448104 |
| 16 | 13467249 |
| 17 | 40720970 |
| 18 | 122994566 |
| 19 | 371156622 |
| 20 | 1119161662 |
| 21 | 3372427789 |
| 22 | 10156591942 |
| 23 | 30573367574 |
| 24 | 91993546765 |
| 25 | 276703494365 |
| 26 | 832023918335 |
| 27 | 2501142914874 |
| 28 | 7516883840470 |