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 | 4 |
| 1 | 11 |
| 2 | 34 |
| 3 | 133 |
| 4 | 566 |
| 5 | 2488 |
| 6 | 11056 |
| 7 | 49323 |
| 8 | 220373 |
| 9 | 985176 |
| 10 | 4405203 |
| 11 | 19699535 |
| 12 | 88096982 |
| 13 | 393978082 |
| 14 | 1761917118 |
| 15 | 7879521402 |
| 16 | 35238270419 |
| 17 | 157590299379 |
| 18 | 704765178272 |
| 19 | 3151805575994 |
| 20 | 14095302829230 |
| 21 | 63036110202947 |