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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 18 |
| 5 | 55 |
| 6 | 174 |
| 7 | 570 |
| 8 | 1908 |
| 9 | 6473 |
| 10 | 22202 |
| 11 | 76886 |
| 12 | 268352 |
| 13 | 942651 |
| 14 | 3329608 |
| 15 | 11817582 |
| 16 | 42120340 |
| 17 | 150682450 |
| 18 | 540832274 |
| 19 | 1946892842 |
| 20 | 7027047848 |
| 21 | 25424079339 |
| 22 | 92185846608 |
| 23 | 334925007128 |
| 24 | 1219054432490 |
| 25 | 4444545298879 |
| 26 | 16229462702152 |
| 27 | 59347661054364 |