# A024718 (b-file synthesized from sequence entry) 0 1 1 2 2 5 3 15 4 50 5 176 6 638 7 2354 8 8789 9 33099 10 125477 11 478193 12 1830271 13 7030571 14 27088871 15 104647631 16 405187826 17 1571990936 18 6109558586 19 23782190486 20 92705454896 21 361834392116 22 1413883873976 23 5530599237776 24 21654401079326 25 84859704298202 26 332818970772254