Alternating sum of (n+1)*A000108(n+1).

Terms

a(0) =1a(1) =3a(2) =12a(3) =44a(4) =166a(5) =626a(6) =2377a(7) =9063a(8) =34695a(9) =133265a(10) =513381a(11) =1982763a(12) =7674937a(13) =29767223a(14) =115655452a(15) =450067268a(16) =1753894162a(17) =6843602438a(18) =26734398172a(19) =104548010228a(20) =409243597192