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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 13 |
| 4 | 42 |
| 5 | 138 |
| 6 | 491 |
| 7 | 1734 |
| 8 | 6612 |
| 9 | 24870 |
| 10 | 97583 |
| 11 | 380218 |
| 12 | 1541360 |
| 13 | 6179237 |
| 14 | 25482059 |
| 15 | 104303570 |
| 16 | 437439838 |
| 17 | 1819760781 |
| 18 | 7724694109 |
| 19 | 32573638812 |
| 20 | 139701430732 |
| 21 | 595473172306 |
| 22 | 2576042993462 |
| 23 | 11082594563917 |
| 24 | 48289942147271 |
| 25 | 209383081359099 |
| 26 | 918120665994465 |
| 27 | 4007798506498828 |
| 28 | 17669572450129852 |
[1,2,5,13,42,138,491,1734,6612,24870,97583,380218, 1541360,6179237,25482059,104303570,437439838, 1819760781,7724694109,32573638812,139701430732, 595473172306,2576042993462,11082594563917, 48289942147271,209383081359099,918120665994465, 4007798506498828,17669572450129852] |