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 | 2 |
| 2 | 5 |
| 3 | 18 |
| 4 | 91 |
| 5 | 574 |
| 6 | 4199 |
| 7 | 34650 |
| 8 | 318645 |
| 9 | 3237034 |
| 10 | 36041657 |
| 11 | 436713506 |
| 12 | 5722676895 |
| 13 | 80654047942 |
| 14 | 1216703923147 |
| 15 | 19562850695690 |
| 16 | 333991034593833 |
| 17 | 6034449711055890 |
| 18 | 115036771019660269 |
| 19 | 2307582082535387570 |
| 20 | 48588759062255598563 |
| 21 | 1071533741191907032590 |