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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 11 |
| 5 | 42 |
| 6 | 153 |
| 7 | 610 |
| 8 | 2459 |
| 9 | 10252 |
| 10 | 43409 |
| 11 | 187057 |
| 12 | 816018 |
| 13 | 3600270 |
| 14 | 16030706 |
| 15 | 71959064 |
| 16 | 325263050 |
| 17 | 1479270802 |
| 18 | 6764056992 |
| 19 | 31078467690 |
| 20 | 143411844050 |
| 21 | 664352697921 |
| 22 | 3088451702294 |
| 23 | 14403683874057 |
| 24 | 67371591912847 |
| 25 | 315969606711112 |
| 26 | 1485546933158293 |
| 27 | 7000321009422438 |
| 28 | 33057274408834760 |
[1,1,4,11,42,153,610,2459,10252,43409,187057, 816018,3600270,16030706,71959064,325263050, 1479270802,6764056992,31078467690,143411844050, 664352697921,3088451702294,14403683874057, 67371591912847,315969606711112,1485546933158293, 7000321009422438,33057274408834760] |