a(n) = Sum_{k=0..n} (k-n)^k.

Terms

a(0) =1a(1) =1a(2) =0a(3) =0a(4) =1a(5) =-1a(6) =0a(7) =6a(8) =-19a(9) =29a(10) =48a(11) =-524a(12) =2057a(13) =-3901a(14) =-9632a(15) =129034a(16) =-664363a(17) =1837905a(18) =2388688a(19) =-67004696a(20) =478198545a(21) =-1994889945a(22) =1669470784a(23) =56929813934a(24) =-615188040195