328831domain: NAppears in sequencesNumbers k such that the period of the continued fraction for sqrt(k) contains exactly 77 ones.at n=29A031845G.f.: Sum_{n>=0} x^n * (d/dx)^(n^2) x^(n^2) * (1+x)^n / (n^2)!, where (d/dx)^k denotes the k-th derivative operator.at n=9A264416