A067456 Floor( sqrt( sum of the decimal digits of n squared)).

1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 2, 2, 2, 3, 4, 5, 6, 7, 8, 9, 3, 3, 3, 4, 5, 5, 6, 7, 8, 9, 4, 4, 4, 5, 5, 6, 7, 8, 8, 9, 5, 5, 5, 5, 6, 7, 7, 8, 9, 10, 6, 6, 6, 6, 7, 7, 8, 9, 10, 10, 7, 7, 7, 7, 8, 8, 9, 9, 10, 11, 8, 8, 8, 8, 8, 9, 10, 10, 11, 12, 9, 9, 9, 9, 9, 10, 10, 11