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 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 26 |
| 6 | 136 |
| 7 | 784 |
| 8 | 5189 |
| 9 | 40639 |
| 10 | 357638 |
| 11 | 3472240 |
| 12 | 37835023 |
| 13 | 449901885 |
| 14 | 5763035223 |
| 15 | 79697811456 |
| 16 | 1185091117180 |
| 17 | 18789393725696 |
| 18 | 316557520950918 |
| 19 | 5664877511610114 |
| 20 | 106815500916218123 |
| 21 | 2123415404236087790 |