a(n) is the number of inversions in all compositions of n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =4a(5) =14a(6) =42a(7) =118a(8) =314a(9) =806a(10) =2010a(11) =4902a(12) =11738a(13) =27686a(14) =64474a(15) =148518a(16) =338906a(17) =767014a(18) =1723354a(19) =3847206a(20) =8539098a(21) =18854950a(22) =41438170a(23) =90682406a(24) =197675994a(25) =429372454a(26) =929582042a(27) =2006430758a(28) =4318579674a(29) =9270965286