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 | 4 |
| 2 | 19 |
| 3 | 103 |
| 4 | 634 |
| 5 | 4393 |
| 6 | 33893 |
| 7 | 288158 |
| 8 | 2674849 |
| 9 | 26888251 |
| 10 | 290614732 |
| 11 | 3356438587 |
| 12 | 41203019361 |
| 13 | 535141595208 |
| 14 | 7324289215167 |
| 15 | 105271669493307 |
| 16 | 1584113665608394 |
| 17 | 24890073684310405 |
| 18 | 407378999173905545 |
| 19 | 6930779764599424550 |
| 20 | 122334506551009552893 |
| 21 | 2236412875771806004767 |