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 | 7 |
| 5 | 20 |
| 6 | 65 |
| 7 | 232 |
| 8 | 883 |
| 9 | 3581 |
| 10 | 15383 |
| 11 | 69579 |
| 12 | 329769 |
| 13 | 1631137 |
| 14 | 8391824 |
| 15 | 44777342 |
| 16 | 247182082 |
| 17 | 1408611456 |
| 18 | 8270902948 |
| 19 | 49953724226 |
| 20 | 309870713560 |
| 21 | 1971523962002 |
| 22 | 12849924998486 |
| 23 | 85702472618249 |
| 24 | 584305721381119 |
| 25 | 4068533850711783 |
| 26 | 28907888594859403 |