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 | 3 |
| 2 | 14 |
| 3 | 76 |
| 4 | 444 |
| 5 | 2702 |
| 6 | 16840 |
| 7 | 106389 |
| 8 | 676566 |
| 9 | 4307754 |
| 10 | 27333384 |
| 11 | 172040544 |
| 12 | 1068547788 |
| 13 | 6505380072 |
| 14 | 38446578888 |
| 15 | 217095119499 |
| 16 | 1136270066490 |
| 17 | 5125578859296 |
| 18 | 15040187738184 |
| 19 | -47786768551830 |
| 20 | -1453703259770520 |
| 21 | -18311261482519860 |
| 22 | -186896777677695720 |