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

1,1

Comments

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

Links

Table of n, a(n) for n=1..34.

Example

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

Crossrefs

Cf. A005346, A121385.

Sequence in context: A036641 A260732 A062425 * A007777 A082379 A167379

Adjacent sequences: A121383 A121384 A121385 * A121387 A121388 A121389

Keyword

nonn

Author

Steve Butler, Jul 26 2006

Extensions

Definition corrected by Rob Pratt, Jun 11 2014

Status

approved