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 | 5 |
| 3 | 29 |
| 4 | 198 |
| 5 | 1469 |
| 6 | 11518 |
| 7 | 93875 |
| 8 | 787392 |
| 9 | 6752175 |
| 10 | 58929541 |
| 11 | 521718814 |
| 12 | 4674070602 |
| 13 | 42296077935 |
| 14 | 386027716280 |
| 15 | 3549332631052 |
| 16 | 32845586854208 |
| 17 | 305685481682970 |
| 18 | 2859315003009776 |
| 19 | 26866125820982711 |
| 20 | 253457922829307765 |
| 21 | 2399910588283502630 |