Happy? := proc( n )
        if n = 1 then
                true
        elif n = 4 then
                false
        else
                local s := SumSqDigits( n );
                while not ( s in { 1, 4 } ) do
                        s := SumSqDigits( s )
                end do;
                evalb( s = 1 )
        end if
end proc: