Numbers having four 0's in base 4.

Terms

a(0) =256a(1) =512a(2) =768a(3) =1025a(4) =1026a(5) =1027a(6) =1028a(7) =1032a(8) =1036a(9) =1040a(10) =1056a(11) =1072a(12) =1088a(13) =1152a(14) =1216a(15) =1280a(16) =1536a(17) =1792a(18) =2049a(19) =2050a(20) =2051a(21) =2052a(22) =2056a(23) =2060a(24) =2064a(25) =2080a(26) =2096a(27) =2112a(28) =2176a(29) =2240