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

Terms

a(0) =2a(1) =2a(2) =-2a(3) =-10a(4) =-4a(5) =20a(6) =12a(7) =-36a(8) =-26a(9) =54a(10) =42a(11) =-78a(12) =-64a(13) =104a(14) =88a(15) =-136a(16) =-118a(17) =170a(18) =150a(19) =-210a(20) =-188a(21) =252a(22) =228a(23) =-300a(24) =-274a(25) =350a(26) =322a(27) =-406a(28) =-376a(29) =464