First differences of A003063.

Terms

a(0) =0a(1) =2a(2) =10a(3) =38a(4) =130a(5) =422a(6) =1330a(7) =4118a(8) =12610a(9) =38342a(10) =116050a(11) =350198a(12) =1054690a(13) =3172262a(14) =9533170a(15) =28632278a(16) =85962370a(17) =258018182a(18) =774316690a(19) =2323474358a(20) =6971471650a(21) =20916512102a(22) =62753730610a(23) =188269580438a(24) =564825518530