n-th derivative of x^(x^(x^(x^x))) at x=1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =9a(4) =56a(5) =480a(6) =4374a(7) =47894a(8) =574888a(9) =7829424a(10) =116392080a(11) =1901059512a(12) =33564909432a(13) =639562529424