Number of terms in n-th derivative of a function composed with itself 9 times.

Terms

a(0) =1a(1) =1a(2) =9a(3) =45a(4) =201a(5) =735a(6) =2517a(7) =7785a(8) =22857a(9) =63024a(10) =166819a(11) =422537a(12) =1035971a(13) =2456694a(14) =5672347a(15) =12756334a(16) =28053280a(17) =60371967a(18) =127479247a(19) =264311585a(20) =539102751a(21) =1082474167a(22) =2142579168a(23) =4183251750a(24) =8064722973a(25) =15360809911a(26) =28928858208a(27) =53896616704a(28) =99398216733