G.f. A(x) satisfies: A(x) = Sum_{n>=0} x^n / (1 - x^(n+1)*A(x)).

Terms

a(0) =1a(1) =2a(2) =4a(3) =11a(4) =33a(5) =111a(6) =395a(7) =1461a(8) =5565a(9) =21654a(10) =85694a(11) =343819a(12) =1395221a(13) =5716363a(14) =23613391a(15) =98238069a(16) =411241397a(17) =1730976298a(18) =7321464729a(19) =31102459844a(20) =132645440213a(21) =567712900716