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 | 0 |
| 1 | 3 |
| 2 | 18 |
| 3 | 118 |
| 4 | 829 |
| 5 | 6115 |
| 6 | 46736 |
| 7 | 366912 |
| 8 | 2941528 |
| 9 | 23981628 |
| 10 | 198224910 |
| 11 | 1657364566 |
| 12 | 13992405626 |
| 13 | 119118427610 |
| 14 | 1021399476720 |
| 15 | 8813544248100 |
| 16 | 76475285228304 |
| 17 | 666865500290884 |
| 18 | 5840843616021192 |
| 19 | 51361847992315320 |
| 20 | 453282040123194425 |
| 21 | 4013440075484640675 |