Expansion of (A(x)^2 - A(x^2))/2 where A(x) = A000108(x) - 1.

Terms

a(0) =0a(1) =0a(2) =0a(3) =2a(4) =6a(5) =24a(6) =80a(7) =286a(8) =994a(9) =3536a(10) =12576a(11) =45220a(12) =163372a(13) =594320a(14) =2172768a(15) =7983990a(16) =29464010a(17) =109174560a(18) =405990464a(19) =1514797020a(20) =5669004692a(21) =21275014800a(22) =80047213792a(23) =301892460012