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 | 5 |
| 2 | 21 |
| 3 | 83 |
| 4 | 319 |
| 5 | 1209 |
| 6 | 4551 |
| 7 | 17085 |
| 8 | 64125 |
| 9 | 240995 |
| 10 | 907741 |
| 11 | 3428655 |
| 12 | 12990121 |
| 13 | 49370963 |
| 14 | 188229489 |
| 15 | 719805987 |
| 16 | 2760498351 |
| 17 | 10615101273 |
| 18 | 40920439119 |
| 19 | 158106581157 |
| 20 | 612166272291 |
| 21 | 2374756691313 |
| 22 | 9228369037659 |
| 23 | 35918537840577 |