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 | 1 |
| 3 | 4 |
| 4 | 20 |
| 5 | 158 |
| 6 | 1539 |
| 7 | 16970 |
| 8 | 199879 |
| 9 | 2460350 |
| 10 | 31266165 |
| 11 | 407461893 |
| 12 | 5420228329 |
| 13 | 73352481577 |
| 14 | 1007312969202 |
| 15 | 14008437540003 |
| 16 | 196963172193733 |
| 17 | 2796235114720116 |
| 18 | 40038505601111596 |
| 19 | 577693117173844307 |
| 20 | 8392528734991449808 |
| 21 | 122680472402091278920 |
| 22 | 1803416089912665770579 |