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 | 3 |
| 4 | 6 |
| 5 | 17 |
| 6 | 49 |
| 7 | 147 |
| 8 | 459 |
| 9 | 1476 |
| 10 | 4856 |
| 11 | 16282 |
| 12 | 55466 |
| 13 | 191474 |
| 14 | 668510 |
| 15 | 2356944 |
| 16 | 8380944 |
| 17 | 30025814 |
| 18 | 108289093 |
| 19 | 392871484 |
| 20 | 1432934360 |
| 21 | 5251507624 |
| 22 | 19329771911 |
| 23 | 71430479820 |
| 24 | 264914270527 |
| 25 | 985737417231 |
| 26 | 3679051573264 |
| 27 | 13769781928768 |
| 28 | 51670641652576 |