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 | 4 |
| 3 | 26 |
| 4 | 220 |
| 5 | 2203 |
| 6 | 24836 |
| 7 | 306104 |
| 8 | 4047988 |
| 9 | 56713521 |
| 10 | 834286612 |
| 11 | 12801754120 |
| 12 | 203889888832 |
| 13 | 3357619794321 |
| 14 | 56999146850380 |
| 15 | 995081586539016 |
| 16 | 17830012791062632 |
| 17 | 327376145842252333 |
| 18 | 6151225530281186372 |
| 19 | 118142009771446643592 |
| 20 | 2317165307900630229384 |