[seqfan] Re: Self-duplication

[N. J. A. Sloane]

D. H. Lehmer once published a sequence in a paper,
and then a few years later the same sequence appeared in another 
paper he wrote in a different context (the second paper was joint 
with Ron Graham).  He didn't realize the two sequences were the same
until I pointed this out. This happened in
the years between the publication of the Handbook of
Integer Sequences and the Encyclopedia of Integer Sequences.
See A003112 for details.
Neil