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 | 18 |
| 2 | 159 |
| 3 | 942 |
| 4 | 4311 |
| 5 | 16536 |
| 6 | 55898 |
| 7 | 171924 |
| 8 | 491487 |
| 9 | 1325546 |
| 10 | 3409347 |
| 11 | 8430246 |
| 12 | 20164223 |
| 13 | 46880424 |
| 14 | 106350942 |
| 15 | 236147828 |
| 16 | 514553154 |
| 17 | 1102562952 |
| 18 | 2327442276 |
| 19 | 4847463408 |
| 20 | 9974081130 |
| 21 | 20297335340 |