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 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 17 |
| 5 | 69 |
| 6 | 299 |
| 7 | 1805 |
| 8 | 9099 |
| 9 | 37331 |
| 10 | 205559 |
| 11 | 4853529 |
| 12 | 49841615 |
| 13 | 789513659 |
| 14 | 9021065871 |
| 15 | 70737031469 |
| 16 | 420565124399 |
| 17 | 22959075244095 |
| 18 | 385032305178719 |
| 19 | 10010973102879761 |
| 20 | 152163983393187399 |
| 21 | 1498273284120348539 |
| 22 | 15639918041915598815 |
| 23 | 1296204202723400597109 |