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 | 18 |
| 4 | 123 |
| 5 | 1098 |
| 6 | 11806 |
| 7 | 150406 |
| 8 | 2218065 |
| 9 | 37206485 |
| 10 | 699604235 |
| 11 | 14572941915 |
| 12 | 333037896380 |
| 13 | 8283300923765 |
| 14 | 222714069807495 |
| 15 | 6436292165450693 |
| 16 | 198941178161054798 |
| 17 | 6548632634238445779 |
| 18 | 228705772883364303114 |
| 19 | 8446082393596031365629 |
| 20 | 328846269698068735291665 |
| 21 | 13462627492562640070346824 |