A trisection of A024495.

Terms

a(0) =0a(1) =3a(2) =21a(3) =171a(4) =1365a(5) =10923a(6) =87381a(7) =699051a(8) =5592405a(9) =44739243a(10) =357913941a(11) =2863311531a(12) =22906492245a(13) =183251937963