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 | 3 |
| 3 | 14 |
| 4 | 80 |
| 5 | 514 |
| 6 | 3567 |
| 7 | 26153 |
| 8 | 199900 |
| 9 | 1579107 |
| 10 | 12816020 |
| 11 | 106421359 |
| 12 | 901430144 |
| 13 | 7771535382 |
| 14 | 68085001080 |
| 15 | 605420138920 |
| 16 | 5459655601753 |
| 17 | 49904765136264 |
| 18 | 462228258349278 |
| 19 | 4337787743946224 |
| 20 | 41249375376404380 |
| 21 | 397572319756235577 |