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) |
|---|---|
| 1 | 5 |
| 2 | 21 |
| 3 | 142 |
| 4 | 840 |
| 5 | 4282 |
| 6 | 18460 |
| 7 | 116615 |
| 8 | 703919 |
| 9 | 3657355 |
| 10 | 16159899 |
| 11 | 95479298 |
| 12 | 588467880 |
| 13 | 3115779158 |
| 14 | 14092223060 |
| 15 | 77925646825 |
| 16 | 490757504161 |
| 17 | 2647731283685 |
| 18 | 12245345216181 |
| 19 | 63384393297262 |
| 20 | 408260456356200 |
| 21 | 2244457157941402 |
| 22 | 10605018345084220 |