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 | 6 |
| 2 | 57 |
| 3 | 488 |
| 4 | 4140 |
| 5 | 34128 |
| 6 | 276792 |
| 7 | 2208312 |
| 8 | 17389710 |
| 9 | 135354340 |
| 10 | 1042965042 |
| 11 | 7964675400 |
| 12 | 60337114778 |
| 13 | 453795079932 |
| 14 | 3390657365970 |
| 15 | 25182770127240 |
| 16 | 186007882964211 |
| 17 | 1366948744701066 |
| 18 | 9998341947058175 |
| 19 | 72811720605519840 |
| 20 | 528078809473488744 |
| 21 | 3815340122599096360 |