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 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 203 |
| 7 | 877 |
| 8 | 4140 |
| 9 | 21146 |
| 10 | 115938 |
| 11 | 677765 |
| 12 | 4200011 |
| 13 | 27446229 |
| 14 | 188255890 |
| 15 | 1349652560 |
| 16 | 10075332564 |
| 17 | 78052115894 |
| 18 | 625568350179 |
| 19 | 5173033558415 |
| 20 | 44028767332852 |
| 21 | 384857341649657 |