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 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 23 |
| 6 | 110 |
| 7 | 607 |
| 8 | 3742 |
| 9 | 25324 |
| 10 | 185566 |
| 11 | 1457998 |
| 12 | 12195992 |
| 13 | 108010446 |
| 14 | 1008224881 |
| 15 | 9883048933 |
| 16 | 101418491070 |
| 17 | 1086613660608 |
| 18 | 12126900841444 |
| 19 | 140682966122152 |
| 20 | 1693340044490513 |
| 21 | 21111988598271746 |
| 22 | 272228110567491910 |
| 23 | 3625334790162237116 |