A130838 - OEIS

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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

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OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..31.

Index entries for doubling substrings

CROSSREFS

Sequence in context: A199357 A293872 A044344 * A225189 A044725 A265948

Adjacent sequences: A130835 A130836 A130837 * A130839 A130840 A130841

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 22 2008

STATUS

approved