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 | 876 |
| 8 | 4120 |
| 9 | 20883 |
| 10 | 113034 |
| 11 | 648410 |
| 12 | 3917021 |
| 13 | 24785452 |
| 14 | 163525976 |
| 15 | 1120523114 |
| 16 | 7947399981 |
| 17 | 58172358642 |
| 18 | 438300848329 |
| 19 | 3391585460591 |
| 20 | 26898763482122 |