1,2
This provides an upper bound on the number of left-associated formulas in O'Connor's puzzle, size of the free cartesian closed category over 3 objects.
Michael O'Connor, An Interesting Puzzle in Propositional Logic, April 9, 2009.
a(2) = 2^26. a(3) = 3^83. a(4) = 2^388.
Sequence in context: A138085 A011576 A089081 * A203670 A183707 A158890
Adjacent sequences: A161771 A161772 A161773 * A161775 A161776 A161777
easy,nonn
Jonathan Vos Post (jvospost3(AT)gmail.com), Jun 18 2009
