Related to discordant permutations.

Terms

a(0) =1a(1) =-3a(2) =5a(3) =-3a(4) =9a(5) =-3a(6) =-51a(7) =-675a(8) =-5871a(9) =-46467a(10) =-331371a(11) =-1852227a(12) =-920295a(13) =224455293a(14) =5571057501a(15) =104877816093