a(n) = 7*6*5*4*3*2*1 - 14*13*12*11*10*9*8 + 21*20*19*18*17*16*15 - ... + (up to the n-th term).

Terms

a(0) =7a(1) =42a(2) =210a(3) =840a(4) =2520a(5) =5040a(6) =5040a(7) =5026a(8) =4858a(9) =2856a(10) =-18984a(11) =-235200a(12) =-2157120a(13) =-17292240a(14) =-17292219a(15) =-17291820a(16) =-17284260a(17) =-17148600a(18) =-14850360a(19) =21777840a(20) =568758960a(21) =568758932a(22) =568758204a(23) =568739304a(24) =568267560a(25) =556965360a(26) =297506160a(27) =-5398802640a(28) =-5398802605