[seqfan] Alphabetical digits

franktaw at netscape.net franktaw at netscape.net
Sat Mar 14 04:26:45 CET 2009

I don't fully understand A072809: Abntu sequence (Bantu alphabetized): 
numbers whose digits are in alphabetical order excluding twos.

First, why the exclusion of twos?  This seems completely arbitrary.

Second, why are the numbers in the sequence in the order that they are 
in?  I would expect them to be in increasing order from the definition, 
but they aren't.  It looks like what was done was to take each number 
(excluding those with twos), and alphabetize its digits -- so each two 
digit number with distinct digits is present twice.  If that is what is 
wanted, the description should say so.

Third, why are one digit numbers not present?

Note that, if all of these are changed, we get A053432.

A final note: the link in this sequence seems to be broken.

Franklin T. Adams-Watters

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