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 | 1 |
| 2 | 6 |
| 3 | 25 |
| 4 | 126 |
| 5 | 649 |
| 6 | 3486 |
| 7 | 19138 |
| 8 | 107233 |
| 9 | 610358 |
| 10 | 3521260 |
| 11 | 20547836 |
| 12 | 121095602 |
| 13 | 719833595 |
| 14 | 4311542748 |
| 15 | 25999063108 |
| 16 | 157723186593 |
| 17 | 962014388419 |
| 18 | 5896435229442 |
| 19 | 36301479759571 |
| 20 | 224396764731302 |
| 21 | 1392253538833522 |