# Yamātārājabhānasalagā

On the edge of our plenum you see a special arrangement of zeros and ones made of wood. Think of any sequence of exactly six zeros and ones, e.g. 100110. Search for the sequence you have made up on the edge of the room. Can you find it only once? This wooden sequence of zeros and ones is an example of a so-called de Bruijn sequence.

The Sanskrit artificial word Yamātārājabhānasalagā, which we have chosen as a name, also describes a de Bruijn sequence, here of short and long syllables. If we look only at the vowels, we get the sequence

a ā ā ā a ā a a a ā.

In it, each three-element subsequence occurs exactly once:

a ā ā, ā ā ā, ā ā a, ā a ā, a ā a, ā a a, a a a, a a ā.

The back of the plenum explains how this sequence is constructed.

How the sequence of digits is built on the plenum border

Stand behind the plenary. Place your hands on two of the wooden numbers on the top edge, so that exactly four numbers are free between them. Feel if there is a zero or a one under your left hand. Now you can predict which digit will result if you move your right hand one digit to the right. If there is a one under your left hand, then the digit on the right changes. If there is a zero on the left, it stays the same. After you have moved your right hand one digit further, also move your left hand one digit to the right, so that again four digits remain free between the two hands. You can now repeat the same rule. This way you get the whole sequence except for the last digit.