409620domain: NAppears in sequencesa(n) = A000905(n) + 1.at n=6A006719Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 64.at n=19A031742a(n) = 400*n^2 + 20.at n=32A158601Transform of the finite sequence (1, 0, -1, 0, 1, 0, -1) by the T_{0,1} transform (see link).at n=15A159342