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 | 4 |
| 3 | 20 |
| 4 | 115 |
| 5 | 719 |
| 6 | 4766 |
| 7 | 32973 |
| 8 | 235381 |
| 9 | 1721159 |
| 10 | 12826228 |
| 11 | 97055181 |
| 12 | 743724984 |
| 13 | 5759636510 |
| 14 | 45007066269 |
| 15 | 354426847597 |
| 16 | 2809934352700 |
| 17 | 22409533673568 |
| 18 | 179655930440464 |
| 19 | 1447023384581029 |
| 20 | 11703780079612453 |
| 21 | 95020085893954917 |
| 22 | 774088023431472074 |