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 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 44 |
| 5 | 308 |
| 6 | 2391 |
| 7 | 22851 |
| 8 | 241570 |
| 9 | 2937179 |
| 10 | 39192998 |
| 11 | 579482352 |
| 12 | 9328260061 |
| 13 | 162563246381 |
| 14 | 3062996934322 |
| 15 | 61499850730949 |
| 16 | 1327236820161040 |
| 17 | 30176760155713420 |
| 18 | 733829463528115523 |
| 19 | 18639130961053854975 |
| 20 | 504241689606231891890 |