Composite numbers whose prime factors contain no digits other than 1 and 6.

Terms

a(0) =121a(1) =671a(2) =1331a(3) =3721a(4) =7271a(5) =7381a(6) =14641a(7) =40321a(8) =40931a(9) =73271a(10) =79981a(11) =81191a(12) =122771a(13) =161051a(14) =177221a(15) =183271a(16) =226981a(17) =406321a(18) =436921a(19) =443531a(20) =450241a(21) =680821a(22) =727771a(23) =805981a(24) =879791a(25) =893101a(26) =982771a(27) =1016321a(28) =1227721a(29) =1350481