When expressed in base 3 and then interpreted in base 7, is a multiple of the original number.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =8a(5) =10a(6) =16a(7) =20a(8) =21a(9) =32a(10) =40a(11) =50a(12) =80a(13) =100a(14) =150a(15) =160a(16) =210a(17) =320a(18) =338a(19) =400a(20) =450a(21) =800a(22) =882a(23) =1014a(24) =1040a(25) =1554a(26) =1600a(27) =4662a(28) =5350a(29) =8636