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 | 9 |
| 3 | 73 |
| 4 | 593 |
| 5 | 4817 |
| 6 | 39129 |
| 7 | 317849 |
| 8 | 2581921 |
| 9 | 20973217 |
| 10 | 170367657 |
| 11 | 1383914473 |
| 12 | 11241683441 |
| 13 | 91317382001 |
| 14 | 741780739449 |
| 15 | 6025563297593 |
| 16 | 48946287120193 |
| 17 | 397595860259137 |
| 18 | 3229713169193289 |
| 19 | 26235301213805449 |
| 20 | 213112122879636881 |