a(n) = [x^n] Product_{k=1..n} (1 - x^k)^(n-k+1).

Terms

a(0) =1a(1) =-1a(2) =0a(3) =4a(4) =-7a(5) =0a(6) =13a(7) =10a(8) =-92a(9) =21a(10) =720a(11) =-2019a(12) =1193a(13) =6281a(14) =-18054a(15) =16111a(16) =11059a(17) =-14653a(18) =-57685a(19) =-86620a(20) =1281406a(21) =-3454742a(22) =2383734a(23) =9409968a(24) =-30397071a(25) =43327680a(26) =-56130326a(27) =128981571a(28) =-73487834a(29) =-1219918457