Expansion of g.f. 2*x / ((1+x)^2*(1-2*x)^2).

Terms

a(0) =2a(1) =4a(2) =14a(3) =32a(4) =82a(5) =188a(6) =438a(7) =984a(8) =2202a(9) =4852a(10) =10622a(11) =23056a(12) =49762a(13) =106796a(14) =228166a(15) =485448a(16) =1029162a(17) =2174820a(18) =4582670a(19) =9631360a(20) =20194802a(21) =42253724a(22) =88235734a(23) =183927992a(24) =382769082a(25) =795364308a(26) =1650380958a(27) =3420066544a(28) =7078742402a(29) =14634703372