MathDB
number of sequences consisting of 12 numbers with 0s and 1s

Source: Nordic Mathematical Contest 1995 #2

October 4, 2017
BinarycombinatoricsInteger sequence

Problem Statement

Messages are coded using sequences consisting of zeroes and ones only. Only sequences with at most two consecutive ones or zeroes are allowed. (For instance the sequence 011001011001 is allowed, but 011101011101 is not.) Determine the number of sequences consisting of exactly 1212 numbers.