Triplets: base 10 representation is the juxtaposition of three identical strings.

Terms

a(0) =111a(1) =222a(2) =333a(3) =444a(4) =555a(5) =666a(6) =777a(7) =888a(8) =999a(9) =101010a(10) =111111a(11) =121212a(12) =131313a(13) =141414a(14) =151515a(15) =161616a(16) =171717a(17) =181818a(18) =191919a(19) =202020a(20) =212121a(21) =222222a(22) =232323a(23) =242424a(24) =252525a(25) =262626a(26) =272727a(27) =282828a(28) =292929a(29) =303030