Fwd: Enumerating emirps all of whose digits are odd

[Jonathan Post]

I am very confused now between the old and new email addresses. Is this one
right?

---------- Forwarded message ----------
From: Jonathan Post <jvospost3 at gmail.com>
Date: Dec 4, 2006 2:24 PM
Subject: Re: Enumerating emirps all of whose digits are odd
To: seqfans at seqfan.net
Cc: jonathan post <jvospost2 at yahoo.com>

The emirpimes analogue being:

15, 39, 51, 93, 115, 155, 159, 177, 319, 335, 339, 355, 511, 533, 551, 553,
...

and, again, there must be an even number of these with n digits, for any
nonnegative integer n.

On 12/4/06, Jonathan Post < jvospost3 at gmail.com> wrote:
>
> Depending of whether you love or hate base sequences, this is pretty or
> ugly.
>
> 13, 17, 31, 37, 71, 73, 79, 97, 113, 157, 179, 199, 311, 337, 359, 733,
> 739, 751, 937, 953, 971, 991, 1153, 1193, ...
>
> a(n) = Emirps all of whose digits are odd.  A006567 INTERSECTION A030096.
>
> How many of these are there for n digits, referred to as b(n) here?  We
> have by inspection:
> b(1) = 0, b(2) = 8, b(3) = 14, and obviously b(n) is always even.
>
> There is the emiprimes analogue, but even more of you might find that
> ugly.
>
> -- Jonathan
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.seqfan.eu/pipermail/seqfan/attachments/20061204/d9fb7aef/attachment-0001.htm>