Right so James
I've pulled your leg with my previous reply.
SK-2⅞ of course was just bullshit and referred to your comment that the nose of the quest plane is shorter than the one of an SK-3. Short->Lower Number->SK-3->SK-2⅞. Bullshit.
And this one...
\( \huge{SK-(2+{{\sum\limits_{n=1}^\infty{1\over{n!}}}\over{e}})} \)
...is just a little math around
Euler's Number e.
e is defined as the as the sum of the infinite series...
\( \huge{e = \sum\limits_{n=1}^\infty{1\over{n!}}} \)
...and can as well be written in a couple of other ways, but given the equation shown above, my formula boils down to...
\( \huge{SK - ( 2 + {e \over e} )} \)
...which is...
\( \huge{SK - ( 2 + 1 ) = SK-3} \)
...and that's just the wrong answer to your quest as you've pointed out before.
Cheers!
Mike