[seqfan] Proof and formulas wanted for A247239

[Jean-François Alcover]

 Dear SeqFans,

A proof that all terms of A247239 <http://oeis.org/A247239> are integers is
wanted.
(such a proof exceeds my capability!)

It would also be interesting to get a general nontrig formula.
I noticed that rows could be computed as linear recurrences.
Example: a(5,m) = 19*a(5,m-1) - 96*a(5,m-2) + 144*a(5,m-3),
with g.f. = (5 - 60*x + 144*x^2)/(1 - 19*x + 96*x^2 - 144*x^3),
giving the explicit formula a(5,m) = 2^(2n+1) + 3^n + 2^(2n+1)*3^n.

I couldn't  find a general explicit or recurrence formula, or g.f.
Hope an expert will be able to find it...

Jean-François