[seqfan] A091344

[Richard Guy]

A091344 featured in a lecture given here
in Calgary yesterday by Christian Ballot
I'll see if I can get the appropriate
reference(s) from him.  Maybe among
MR 2008i:11117, 2008h:11012, 2009b:11162,
2008a:11116.  But at least should be added
that it's a recurring sequence with
recurrence relation

a_n = 6a_[n-1} - 11a_{n-2} + 6a_{n-3}

and generating function

        x(1+x)/(1-x)(2-x)(3-x)

Later:  I've just spoken to Ballot and he says
that the relevant papers are:

MR2357506 (2008i:11117)
Ballot, Christian(F-CAEN-LM); Luca, Florian(MEX-NAM-IM)
Common prime factors of $a\sp n-b$ and $c\sp n-d$. (English summary)
Unif. Distrib. Theory 2 (2007), no. 2, 19--34 (electronic).
11N37 (11A07)

and

MR2217162 (2007b:11140)
Ballot, Christian(F-CAEN-LM); Luca, Florian
Prime factors of $a\sp {f(n)}-1$ with an irreducible polynomial $f(x)$. 
(English summary)
New York J. Math. 12 (2006), 39--45 (electronic).
11N37 (11B83)

R.