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 | 42 |
| 3 | 315 |
| 4 | 2457 |
| 5 | 19656 |
| 6 | 160056 |
| 7 | 1320462 |
| 8 | 11003850 |
| 9 | 92432340 |
| 10 | 781473420 |
| 11 | 6642524070 |
| 12 | 56716936290 |
| 13 | 486145168200 |
| 14 | 4180848446520 |
| 15 | 36059817851235 |
| 16 | 311811366125385 |
| 17 | 2702365173086670 |
| 18 | 23467908082068450 |
| 19 | 204170800313995515 |
| 20 | 1779202688450532345 |
| 21 | 15527587099204645920 |