A121386 Number of different two-colorings of {1,...,n} that minimize the number of monochromatic three-term arithmetic progressions that such a coloring can contain.

2, 4, 6, 10, 14, 20, 16, 6, 36, 8, 44, 10, 8, 30, 16, 8, 12, 2, 12, 28, 64, 110, 96, 134, 56, 44, 16, 2, 16, 74, 116, 188, 200, 180

Offset: 1

Author

Steve Butler, Jul 26 2006

Keywords

• nonn

Comments

The unique (up to switching colors) sequences for n=18 and n=28 are 001001111000011011 and 0001100011111100000011100111 respectively.

Examples

			a(3)=6 because all non-monochromatic colorings are such an example
		

Crossrefs

Cf. A005346, A121385.

Extensions

Definition corrected by Rob Pratt, Jun 11 2014