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 | 2 |
| 2 | 7 |
| 3 | 30 |
| 4 | 157 |
| 5 | 970 |
| 6 | 6931 |
| 7 | 56294 |
| 8 | 512569 |
| 9 | 5173074 |
| 10 | 57330271 |
| 11 | 692227822 |
| 12 | 9045871957 |
| 13 | 127205130650 |
| 14 | 1915394962027 |
| 15 | 30748771424310 |
| 16 | 524265894691441 |
| 17 | 9461374592096674 |
| 18 | 180184121539899319 |
| 19 | 3611206508019111614 |
| 20 | 75978294135602723341 |
| 21 | 1674381620327287502442 |