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 | 5 |
| 3 | 34 |
| 4 | 267 |
| 5 | 2279 |
| 6 | 20540 |
| 7 | 192350 |
| 8 | 1853255 |
| 9 | 18252079 |
| 10 | 182924645 |
| 11 | 1859546968 |
| 12 | 19127944500 |
| 13 | 198725331588 |
| 14 | 2082256791048 |
| 15 | 21979169545670 |
| 16 | 233495834018591 |
| 17 | 2494624746580655 |
| 18 | 26786319835972799 |
| 19 | 288915128642169250 |
| 20 | 3128814683222599331 |
| 21 | 34007373443388857999 |