Katadromes: digits in base 6 are in strict descending order.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =6a(7) =12a(8) =13a(9) =18a(10) =19a(11) =20a(12) =24a(13) =25a(14) =26a(15) =27a(16) =30a(17) =31a(18) =32a(19) =33a(20) =34a(21) =78a(22) =114a(23) =120a(24) =121a(25) =150a(26) =156a(27) =157a(28) =162a(29) =163