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 | 4 |
| 2 | 26 |
| 3 | 202 |
| 4 | 1731 |
| 5 | 15780 |
| 6 | 150117 |
| 7 | 1473292 |
| 8 | 14807363 |
| 9 | 151638550 |
| 10 | 1576616125 |
| 11 | 16598802248 |
| 12 | 176599380271 |
| 13 | 1895767748376 |
| 14 | 20508188211018 |
| 15 | 223348309510194 |
| 16 | 2446792909432683 |
| 17 | 26944972018189698 |
| 18 | 298111489130625351 |
| 19 | 3312016395569631402 |
| 20 | 36935315970911333184 |
| 21 | 413308467174788509668 |