a(n) = (-1)^n*(A056040(n+1)*A152271(n)-2^n)/2.

Terms

a(0) =0a(1) =0a(2) =1a(3) =-2a(4) =7a(5) =-14a(6) =38a(7) =-76a(8) =187a(9) =-374a(10) =874a(11) =-1748a(12) =3958a(13) =-7916a(14) =17548a(15) =-35096a(16) =76627a(17) =-153254a(18) =330818a(19) =-661636a(20) =1415650a(21) =-2831300a(22) =6015316a(23) =-12030632a(24) =25413342a(25) =-50826684a(26) =106853668a(27) =-213707336a(28) =447472972a(29) =-894945944