a(n) = (-1)^n*(n + 1)*(5*n^2 + 10*n + 1).

Terms

a(0) =1a(1) =-32a(2) =123a(3) =-304a(4) =605a(5) =-1056a(6) =1687a(7) =-2528a(8) =3609a(9) =-4960a(10) =6611a(11) =-8592a(12) =10933a(13) =-13664a(14) =16815a(15) =-20416a(16) =24497a(17) =-29088a(18) =34219a(19) =-39920a(20) =46221a(21) =-53152a(22) =60743a(23) =-69024a(24) =78025a(25) =-87776a(26) =98307a(27) =-109648a(28) =121829a(29) =-134880