Third column of Lucas bisection triangle (even part).

Terms

a(0) =1a(1) =39a(2) =315a(3) =1687a(4) =7470a(5) =29634a(6) =109421a(7) =384105a(8) =1298613a(9) =4264835a(10) =13686456a(11) =43102644a(12) =133636825a(13) =408900987a(14) =1237114335a(15) =3706490479a(16) =11010661266a(17) =32463981270a(18) =95081107013a(19) =276820695645a(20) =801633669561