A130838 Sorted list of strings that can be obtained by starting with 12 and repeatedly doubling any substring in place.

12, 112, 122, 1112, 1122, 1212, 1222, 11112, 11122, 11212, 11222, 12112, 12122, 12212, 12222, 111112, 111122, 111212, 111222, 112112, 112122, 112212, 112222, 121112, 121122, 121212, 121222, 122112, 122122, 122212, 122222

Offset: 1

Author

N. J. A. Sloane, Feb 22 2008

Keywords

• nonn

Comments

The list contains 2^(n-2) strings of length n, namely 1{1,2}^(n-2)2, for n >= 2.

Links

• Index entries for doubling substrings