[seqfan] Re: My first base-10 related question here, I think
Hans Havermann
pxp at rogers.com
Fri Jun 26 20:49:17 CEST 2009
> could someone please send in a correction to A074721, and a b-file
> for it?
Bob: The current comment prior to the "Problem: least k>9 with
a(k)=A000040(k)?" can probably be deleted, as can the link that
supports that part of the comment. A particular method of
factorization is not really pertinent to the sequence.
I just want to bring up something that is not necessarily a problem
for this sequence but I'd like someone's opinion on it regardless.
When the primes 691, 701, 709, and 719 get concatenated and digitized,
we end up with: {..., 6, 9, 1, 7, 0, 1, 7, 0, 9, 7, 1, 9, ...}. These
will end up in A074721 as terms #98 - #102: {691, 7, 17, 97, 19}.
Terms #100 & #101 have associated with them *unstated* leading zeros.
This makes it difficult to construct the concatenated primes from just
the sequence terms. Perhaps a comment to that effect might alert the
unwary. The alternative would be to complicate the definition of the
sequence to exclude leading zeros from existing, not the best solution.
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