"3-Portolan numbers": number of regions formed by n-secting the angles of an equilateral triangle.

Terms

a(0) =1a(1) =6a(2) =19a(3) =30a(4) =61a(5) =78a(6) =127a(7) =150a(8) =217a(9) =234a(10) =331a(11) =366a(12) =469a(13) =510a(14) =631a(15) =678a(16) =817a(17) =870a(18) =1027a(19) =1074a(20) =1261a(21) =1326a(22) =1519a(23) =1590a(24) =1801a(25) =1878a(26) =2107a(27) =2190a(28) =2437a(29) =2514