# A151370 (b-file synthesized from sequence entry) 0 1 1 0 2 2 3 3 4 20 5 60 6 345 7 1400 8 7770 9 36876 10 204876 11 1062600 12 5984352 13 32772168 14 187727826 15 1065491427 16 6206538910 17 36123454224 18 213645926208 19 1266954939822 20 7593846587496 21 45694598654640 22 277066122022872 23 1686973019649060 24 10331412410444280 25 63524084460496480 26 392411097399517800