# A004142 (b-file synthesized from sequence entry) 0 0 1 1 2 10 3 57 4 260 5 1055 6 3990 7 14413 8 50440 9 172539 10 580250 11 1926089 12 6328140 13 20619703 14 66732190 15 214742085 16 687698960 17 2193154547 18 6968850210 19 22073006401 20 69714716500 21 219623377071 22 690291036710