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 | 5 |
| 2 | 22 |
| 3 | 90 |
| 4 | 351 |
| 5 | 1323 |
| 6 | 4860 |
| 7 | 17496 |
| 8 | 61965 |
| 9 | 216513 |
| 10 | 747954 |
| 11 | 2558790 |
| 12 | 8680203 |
| 13 | 29229255 |
| 14 | 97785144 |
| 15 | 325241892 |
| 16 | 1076168025 |
| 17 | 3544180029 |
| 18 | 11622614670 |
| 19 | 37967207922 |
| 20 | 123587135991 |
| 21 | 400980206115 |
| 22 | 1297083797172 |
| 23 | 4184141281200 |