a(n) = 3*2*1 - 6*5*4 + 9*8*7 - 12*11*10 + 15*14*13 - 18*17*16 + ... - (up to the n-th term).

Terms

a(0) =3a(1) =6a(2) =6a(3) =0a(4) =-24a(5) =-114a(6) =-105a(7) =-42a(8) =390a(9) =378a(10) =258a(11) =-930a(12) =-915a(13) =-720a(14) =1800a(15) =1782a(16) =1494a(17) =-3096a(18) =-3075a(19) =-2676a(20) =4884a(21) =4860a(22) =4332a(23) =-7260a(24) =-7233a(25) =-6558a(26) =10290a(27) =10260a(28) =9420a(29) =-14070