I chant integer sequences as lullabies. Soporific for baby, brain exercise for me.
Here's a sequence that I came up with for this afternoon's nap:

1,2,3,2,4,5,4,6,4,7,6,4,8,9,8,10,8,11,10,8,12,8,13,12,8,14,12,8,15,14,12,8,16,17,16,18,16,19,18,16,20,16,21,20,16…

What's next?