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 | 3 |
| 3 | 13 |
| 4 | 77 |
| 5 | 594 |
| 6 | 5737 |
| 7 | 67216 |
| 8 | 931584 |
| 9 | 14968423 |
| 10 | 274312910 |
| 11 | 5657512947 |
| 12 | 129866646887 |
| 13 | 3287152235160 |
| 14 | 91025011377693 |
| 15 | 2738909774003719 |
| 16 | 89027345548731677 |
| 17 | 3110096516555803509 |
| 18 | 116244489639439112395 |