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 | 4 |
| 2 | 18 |
| 3 | 87 |
| 4 | 442 |
| 5 | 2332 |
| 6 | 12677 |
| 7 | 70605 |
| 8 | 401172 |
| 9 | 2317683 |
| 10 | 13578615 |
| 11 | 80502845 |
| 12 | 482140580 |
| 13 | 2912954129 |
| 14 | 17733375207 |
| 15 | 108676158775 |
| 16 | 669914021414 |
| 17 | 4151053001800 |
| 18 | 25841001981211 |
| 19 | 161534820531068 |
| 20 | 1013566626969398 |
| 21 | 6381398103680604 |
| 22 | 40301852983776764 |
| 23 | 255249505209864803 |
| 24 | 1620819715569894894 |