351089domain: NAppears in sequencesNumbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 47.at n=18A031635G.f.: Sum_{n>=0} x^n * (1 + x^n)^n / (1 + x + x^(n+1))^(n+1).at n=18A322618