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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 14 |
| 6 | 145 |
| 7 | 1450 |
| 8 | 15421 |
| 9 | 180894 |
| 10 | 2359225 |
| 11 | 34072850 |
| 12 | 540848341 |
| 13 | 9363767974 |
| 14 | 175619185105 |
| 15 | 3547113529050 |
| 16 | 76761061273261 |
| 17 | 1771884886830254 |
| 18 | 43456922321543785 |
| 19 | 1128511554354422050 |
| 20 | 30933862439582514181 |
| 21 | 892562598747547111734 |
| 22 | 27041608332832948251265 |
| 23 | 858281473267724898703850 |