A
number is an Eban number if, when written in words, it does not contain the letter "e". The Eban
number sequence is the series of
positive integers which do not have a letter "
e" when written in words:
2, 4, 6, 30, 32, 34, 36, 40, 42, 44, 46, 50, 52, 54, 56, 60...
two, four, six, thirty, thirty-two, thirty-four, thirty-six...
This can exclude a surprisingly large number of integers. There are no Eban numbers between
66 and 2000 (reason: "one thousand and..."), for example.
(ref: The Online Encyclopedia of Integer Sequences at http://www.research.att.com/~njas/sequences/)