E-trees with exactly 3 colors.

Terms

a(0) =0a(1) =0a(2) =0a(3) =16a(4) =177a(5) =1374a(6) =9370a(7) =60582a(8) =383577a(9) =2412331a(10) =15179013a(11) =95860821a(12) =608523299a(13) =3884620950a(14) =24937791531a(15) =160952346541