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 | 4 |
| 2 | 13 |
| 3 | 45 |
| 4 | 212 |
| 5 | 1205 |
| 6 | 7754 |
| 7 | 54033 |
| 8 | 397820 |
| 9 | 3049439 |
| 10 | 24107782 |
| 11 | 195301124 |
| 12 | 1613855392 |
| 13 | 13556782136 |
| 14 | 115465571163 |
| 15 | 995112789441 |
| 16 | 8663956923566 |
| 17 | 76105986001922 |
| 18 | 673776966100254 |
| 19 | 6006525932517904 |
| 20 | 53878729432248978 |