a(n) is the number of edges formed by n-secting the angles of an equilateral triangle.

Terms

a(0) =3a(1) =12a(2) =39a(3) =54a(4) =123a(5) =144a(6) =255a(7) =282a(8) =435a(9) =432a(10) =663a(11) =702a(12) =939a(13) =984a(14) =1263a(15) =1314a(16) =1635a(17) =1692a(18) =2055a(19) =2082a(20) =2523a(21) =2592a(22) =3039a(23) =3114a(24) =3603a(25) =3684a(26) =4215a(27) =4302a(28) =4875a(29) =4932