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) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 27 |
| 5 | 110 |
| 6 | 429 |
| 7 | 1638 |
| 8 | 6188 |
| 9 | 23256 |
| 10 | 87210 |
| 11 | 326876 |
| 12 | 1225785 |
| 13 | 4601610 |
| 14 | 17298645 |
| 15 | 65132550 |
| 16 | 245642760 |
| 17 | 927983760 |
| 18 | 3511574910 |
| 19 | 13309856820 |
| 20 | 50528160150 |
| 21 | 192113383644 |
| 22 | 731508653106 |
| 23 | 2789279908316 |
| 24 | 10649977831752 |
| 25 | 40715807302800 |
| 26 | 155851062397940 |
| 27 | 597261490737912 |