a(n) = a(n-1) - 2*a(n-2) - 3*a(n-3) - ... - (n-1)*a(1), with a(1) = a(2) = 2, a(3) = -2.

Terms

a(0) =2a(1) =2a(2) =-2a(3) =-12a(4) =-22a(5) =-10a(6) =56a(7) =174a(8) =222a(9) =-92a(10) =-1038a(11) =-2210a(12) =-1624a(13) =4102a(14) =16006a(15) =24260a(16) =954a(17) =-86426a(18) =-215528a(19) =-212546a(20) =267150a(21) =1433124a(22) =2538530a(23) =984270a(24) =-6873592a(25) =-20465066a(26) =-25058698a(27) =13402052a(28) =124569514a(29) =256580886