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 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 13 |
| 6 | 42 |
| 7 | 150 |
| 8 | 553 |
| 9 | 2202 |
| 10 | 9233 |
| 11 | 39726 |
| 12 | 176932 |
| 13 | 810798 |
| 14 | 3786137 |
| 15 | 18022100 |
| 16 | 87265298 |
| 17 | 428202617 |
| 18 | 2127088358 |
| 19 | 10684752474 |
| 20 | 54181245592 |
| 21 | 277101480826 |
| 22 | 1428262595206 |
| 23 | 7412626391101 |
| 24 | 38712130945272 |
| 25 | 203330779196084 |