32416037103domain: NAppears in sequencesDefine P(n,X) by the recursion P(1,X) = 1, P(n+1,X) = (P(n,X)+X)^2; then a(1) = 0 and for n > 1 a(n) is the coefficient of X^(2^(n-2)) in P(n,X) of degree 2^(n-1).at n=5A070256