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 | 2 |
| 2 | 6 |
| 3 | 18 |
| 4 | 44 |
| 5 | 110 |
| 6 | 252 |
| 7 | 588 |
| 8 | 1304 |
| 9 | 2934 |
| 10 | 6380 |
| 11 | 14036 |
| 12 | 30120 |
| 13 | 65260 |
| 14 | 138712 |
| 15 | 297240 |
| 16 | 627248 |
| 17 | 1332902 |
| 18 | 2796876 |
| 19 | 5904516 |
| 20 | 12333320 |
| 21 | 25899972 |
| 22 | 53897096 |
| 23 | 112693928 |
| 24 | 233776464 |
| 25 | 487034300 |
| 26 | 1007623032 |
| 27 | 2092755528 |
| 28 | 4319728784 |
| 29 | 8948009624 |
| 30 | 18432890160 |
| 31 | 38094639664 |