Semiprime nearest to 3^n. In case of a tie, choose the smaller.

Terms

a(0) =4a(1) =4a(2) =9a(3) =26a(4) =82a(5) =247a(6) =731a(7) =2186a(8) =6559a(9) =19679a(10) =59047a(11) =177149a(12) =531439a(13) =1594322a(14) =4782979a(15) =14348905a(16) =43046722a(17) =129140159a(18) =387420493a(19) =1162261465a(20) =3486784399a(21) =10460353201a(22) =31381059597a(23) =94143178823a(24) =282429536489a(25) =847288609441