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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 79 |
| 6 | 310 |
| 7 | 1251 |
| 8 | 5150 |
| 9 | 21517 |
| 10 | 90921 |
| 11 | 387595 |
| 12 | 1663936 |
| 13 | 7183750 |
| 14 | 31158310 |
| 15 | 135661904 |
| 16 | 592558096 |
| 17 | 2595232344 |
| 18 | 11392504426 |
| 19 | 50109205789 |
| 20 | 220777103354 |
| 21 | 974162444028 |
| 22 | 4303957562319 |
| 23 | 19036842605855 |
| 24 | 84285643628790 |
| 25 | 373502845338552 |
| 26 | 1656428550764640 |
| 27 | 7351106011540209 |
| 28 | 32643855249507805 |
| 29 | 145040974005303590 |
| 30 | 644756480385363800 |