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 | 2 |
| 3 | 5 |
| 4 | 21 |
| 5 | 129 |
| 6 | 1099 |
| 7 | 11647 |
| 8 | 148292 |
| 9 | 2190302 |
| 10 | 36842892 |
| 11 | 694276152 |
| 12 | 14488348603 |
| 13 | 331537914373 |
| 14 | 8254117606799 |
| 15 | 222087256536602 |
| 16 | 6421589319659283 |
| 17 | 198565371839434761 |
| 18 | 6538245667687424041 |
| 19 | 228396692050813678534 |
| 20 | 8436237099236470594589 |