Trisection of tribonacci numbers.

Terms

a(0) =0a(1) =1a(2) =7a(3) =44a(4) =274a(5) =1705a(6) =10609a(7) =66012a(8) =410744a(9) =2555757a(10) =15902591a(11) =98950096a(12) =615693474a(13) =3831006429a(14) =23837527729a(15) =148323355432a(16) =922906855808