|
EXAMPLE
|
1, 1, 1, 1, 1, 1, 1, 1, 1, 1 ...
2, 2, 2, 2, 2, 2, 2, 2, 2, 2 ...
4, 4, 4, 4, 4, 4, 4, 4, 4, 4 ...
7, 8, 8, 8, 8, 8, 8, 8, 8, 8 ...
13, 16, 16, 16, 16, 16, 16, 16, 16, 16 ...
24, 28, 32, 32, 32, 32, 32, 32, 32, 32 ...
44, 49, 64, 64, 64, 64, 64, 64, 64, 64 ...
81, 91, 112, 128, 128, 128, 128, 128, 128, 128 ...
149, 169, 196, 256, 256, 256, 256, 256, 256, 256 ...
274, 312, 343, 448, 512, 512, 512, 512, 512, 512 ...
504, 576, 637, 784, 1024, 1024, 1024, 1024, 1024, 1024 ...
............................................................
For a(5,2) we count subsets of {1,...,5} that do not contain {1,3,5}, the only d=2 AP possible here. There are 4 subsets containing {1,3,5} so a(5,2) = 2^5-4 = 28.
|