Question 1083635

{{{Q(n) = Q(n -1) + Q(n -2) + Q(n- 3)}}}

 if{{{ n = 5}}}, it means {{{Q(5) = Q(4) + Q(3) + Q(2) }}}

we need the value of  {{{Q(4)}}} and {{{Q(3) }}}

 if {{{n = 3}}}, then {{{Q(3) = Q(2) + Q(1) + Q(0) = 4 + 2 + 0 = 6 }}}
and 

if {{{n = 4}}}, then {{{Q(4) = Q(3) + Q(2) + Q(1) = 6 + 4 + 2 = 12 }}}

therefore, {{{Q(5) = Q(4) + Q(3) + Q(2), Q(5) = 12 + 6 + 4 = 22 }}}