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 | 2 |
| 2 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 44 |
| 6 | 135 |
| 7 | 472 |
| 8 | 1492 |
| 9 | 5324 |
| 10 | 17405 |
| 11 | 63944 |
| 12 | 215096 |
| 13 | 799416 |
| 14 | 2752909 |
| 15 | 10310384 |
| 16 | 36443256 |
| 17 | 137263244 |
| 18 | 489166324 |
| 19 | 1860249448 |
| 20 | 6739795717 |
| 21 | 25596173800 |
| 22 | 93596253769 |
| 23 | 357974884304 |
| 24 | 1319325363658 |
| 25 | 5056389932088 |