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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 98 |
| 6 | 547 |
| 7 | 3556 |
| 8 | 26738 |
| 9 | 227720 |
| 10 | 2170267 |
| 11 | 22877331 |
| 12 | 264314464 |
| 13 | 3320870054 |
| 14 | 45076422125 |
| 15 | 657316885209 |
| 16 | 10247614197601 |
| 17 | 170081414212020 |
| 18 | 2994059471570761 |
| 19 | 55718507205774017 |
| 20 | 1092932100469356250 |
| 21 | 22536709415953547880 |
| 22 | 487361620197926253365 |