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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 11 |
| 4 | 60 |
| 5 | 435 |
| 6 | 3473 |
| 7 | 31315 |
| 8 | 313227 |
| 9 | 3445641 |
| 10 | 41341502 |
| 11 | 537313583 |
| 12 | 7520316423 |
| 13 | 112771887719 |
| 14 | 1803821926465 |
| 15 | 30656189582521 |
| 16 | 551659191788556 |
| 17 | 10478765887885181 |
| 18 | 209522984620760153 |
| 19 | 4398943767896801309 |
| 20 | 96755196700729056267 |
| 21 | 2224901906327124750355 |