Powers of 3 written in base 7.

Terms

a(0) =1a(1) =3a(2) =12a(3) =36a(4) =144a(5) =465a(6) =2061a(7) =6243a(8) =25062a(9) =111246a(10) =334104a(11) =1335315a(12) =4342251a(13) =16360113a(14) =55440342a(15) =232651356a(16) =1031614434a(17) =3125446635a(18) =12413006541a(19) =40542026253a(20) =152256115122a(21) =520134351366