[seqfan] Re: Number of primes having distinct first and last digits both 7 to 10^n primes

[Alois Heinz]

Charles Greathouse schrieb:
> A145711 is defined as "Number of primes having distinct first and last
> digits both 7 to 10^n primes".  It seems to mean something similar to
> "Number of primes below 10^n with distinct first and last decimal
> digits", but this isn't quite it.  Can anyone decipher it?
>   
Cardinality of the set of the first 10^n primes which are
larger than 7 and have both the first and the last decimal digit 7.

a(3)=32, because there are 32 primes in the set, from p(129)=727 to 
p(962)=7577.

The sequence should have keyword base (and less?) and offset 1.

Alois
> >From its description:
> Comment: The first prime with equal first and last digits is 11 -- the
> two digits must be distinct, so 7, for example, cannot be
> double-counted.
> Example: a(3)=32 because to 10^3 or 1000 primes, ending in 7919, there
> are 32 primes with equal and distinct first and last digits: 7 and 7.
>
> It also needs keyword work: it needs "base" but not "easy" (since it
> involves exponentially many terms).
>
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
>
>