A123594 Unique sequence of 0's and 1's which are either repeated or not repeated with the following property: when the sequence is 'coded' in writing down a 1 when an element is repeated and a 0 when it is not repeated and by putting the initial element in front of the sequence thus obtained, the above sequence appears.

1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0

Offset: 1

Author

Emmanuel Vantieghem, Nov 14 2006

Keywords

• easy
• nonn

Links

• Vantieghem Emmanuel, Nov 14 2006, Table of n, a(n) for n = 1..620

Crossrefs

Cf. A000002.

Programs

Mathematica

a = {1, 1, 0}; i = 2; Label[be]; i += 1; t = Part[a, i]; If[t == 0, b = {a, 1 - Part[a, Length[a]]}; a := Flatten[b], b = {a, Part[a, Length[a]]}; a := Flatten[b]; b = {a, 1 - Part[a, Length[a]]}; a := Flatten[b]]; If[i > 1000, Print[a], Goto[be]]

Formula

a(n+2) = A000002(n)-1. - Danny Rorabaugh, Mar 04 2015