Binary expansion contains 3 adjacent 1's.

Terms

a(0) =7a(1) =14a(2) =15a(3) =23a(4) =28a(5) =29a(6) =30a(7) =31a(8) =39a(9) =46a(10) =47a(11) =55a(12) =56a(13) =57a(14) =58a(15) =59a(16) =60a(17) =61a(18) =62a(19) =63a(20) =71a(21) =78a(22) =79a(23) =87a(24) =92a(25) =93a(26) =94a(27) =95a(28) =103a(29) =110