a(5,c)

 0      1	// 2 if the constant boolean functions cost 0 (Knuth)
 1      2	// 1 if the constant boolean functions cost 0 (Knuth)
 2      2
 3      7
 4     21
 5     55
 6    198
 7    667
 8   2311
 9   8094
10  24947
11  68731
12 142470
13 197606
14 138506
15  31733
16    774 or 775
17     1  or 0

D.I.Stevenson February 2016

This calculation took several months using the Clang compiler (C programs) under Linux(Fedora).

The numbers have been verified for costs upto 13 using Visual Studio (C++ program) under Windows.

D.I.Stevenson October 2017