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 | 3 |
| 2 | 15 |
| 3 | 84 |
| 4 | 491 |
| 5 | 2948 |
| 6 | 18018 |
| 7 | 111520 |
| 8 | 696739 |
| 9 | 4384668 |
| 10 | 27753110 |
| 11 | 176494640 |
| 12 | 1126809230 |
| 13 | 7217773800 |
| 14 | 46364184420 |
| 15 | 298554038144 |
| 16 | 1926593569059 |
| 17 | 12455864623020 |
| 18 | 80664529969422 |
| 19 | 523165672201744 |
| 20 | 3397648036150426 |
| 21 | 22092460470618328 |
| 22 | 143809661629562460 |