Each number is the lowest number that hasn’t yet appeared in the sequence, that begins with the last letter of the previous number.

ONE – EIGHT – TWO – ONE HUNDRED – DECILLION – NINE – ELEVEN – NINETEEN - NINETY

No numbers begin with ‘y’.

I realise I’ve been a little inconsistent with names of numbers, allowing 100 to be called ‘one hundred’ but 10^33 as merely ‘decillion’ not ‘one decillion’ but that was the only way!