A127117 A sequence of binary numbers. The first number is 1. Thereafter each number a(n) is defined using the previous number a(n-1) in the following way : a(n)=a(n-1).b(n-1) where the dot means the concatenation operation and b(n-1) stands for the first number that is not present in a(n-1), using the usual order (1, 10, 11, 100, 101, etc.).

1, 10, 1011, 1011100, 10111001000, 101110010001010, 1011100100010101101, 10111001000101011011111, 1011100100010101101111110000, 101110010001010110111111000010011

Offset

1,2

Links

Table of n, a(n) for n=1..10.

Nicolas Wicker, Tcl program

Example

a(3)=1011 because a(2)=10 and 0, 1 and 10 are present in a(2) but 11 is not, so we append 11 to a(2) getting 10.11=1011.

Crossrefs

Sequence in context: A179284 A138484 A022506 * A154703 A172163 A174768

Adjacent sequences: A127114 A127115 A127116 * A127118 A127119 A127120

Keyword

easy,nonn,base

Author

Nicolas Wicker (wicker(AT)igbmc.u-strasbg.fr), Mar 21 2007

Status

approved