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 | 4 |
| 2 | 15 |
| 3 | 60 |
| 4 | 255 |
| 5 | 1128 |
| 6 | 5117 |
| 7 | 23600 |
| 8 | 110115 |
| 9 | 518220 |
| 10 | 2455101 |
| 11 | 11693124 |
| 12 | 55934385 |
| 13 | 268535400 |
| 14 | 1293178275 |
| 15 | 6243968880 |
| 16 | 30217425795 |
| 17 | 146529719100 |
| 18 | 711810105725 |
| 19 | 3463284659300 |
| 20 | 16874328961245 |
| 21 | 82322471522280 |
| 22 | 402079323279975 |
| 23 | 1965900162652800 |
| 24 | 9621179345962525 |
| 25 | 47127880914834148 |